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Questions: Armor Rules

Posted: 06 Sep 2017, 07:31
by FortPwnall
I'd like to know the reasoning behind the rules for armor, especially rigid armor in Sword and Scoundrel / Band of Bastards. They seem pretty strange to me.

I've quoted the relevant rules, as well as some example armor and weapons below.

So, if I'm understanding this correctly, if I slice someone who is wearing a maille coif on the head with a greatsword, all of the slicing damage is converted directly to bashing damage? Whereas if I hit someone wearing a padded coif, it just counts as slicing damage of the same amount? I get that a greatsword can cause some serious blunt force trauma, but is its damage not primarily due to the fact that it is cutting? Should it really be doing the same amount of blunt damage as it would have done cutting damage? Does the damage table make up for this? I.e., is a slice-wound more serious than a similar level bash-wound?

Further, what is with the rigid armor rules, and then the crushing quality? I get the reason for the rule for, like, metal-rigid things, where e.g. the slashing damage is first converted to bashing, and then calculated. So if I smack you really hard on your plate helm with my greatsword, it's not going to dent your skull, but it is going to knock your head around inside, dealing damage in this indirect fashion. Even more so with a full plate. I might knock you over, but I won't necessarily crush your ribs.

It seems that any bashing weapon worth its salt in the table has the crushing quality anyway, but if I bash you really hard with something that doesn't have this quality, like say I bash you with a quarterstaff on your boiled leather cap, then the damage gets capped? Like, my quarterstaff is incapable of smashing through your cap? I don't know much about boiled leather, but since it is "akin to hard plastic sporting pads" I guess I can understand it being impossible without using a "crushing" weapon?

Furthermore, the rules say that any time a character manages to suffer a level 4 or 5 wound through their armor, it’s assumed that that location on their armor has been damaged. Does the cap get calculated before this rule apply? Does it actually mean it is impossible to damage e.g. metal plate with a quarterstaff or greatsword? This is an entirely believable proposition, to be honest. It also implies it is impossible to damage boiled leather similarly. But the rules as-written don't make it terribly clear.

Anyways, I think I kind of understand the reasoning... but I feel like the rules could somehow be simplified or better explained and still achieve the desired effect. Though I am not entirely sure how one would do this. What are your thoughts?

Select Armor Rules
Any time the character is struck, they may subtract the total of their AV and Brawn tap value from any damage taken. Any damage left over becomes the character’s wound level.
Metal (M) armors convert all cutting and piercing damage to the blunt type. If your character is stabbed in a location covered by metal armor the piercing damage changes its type to blunt before you work out the final wound level.
Rigid (R) armors place a cap on all blunt damage at level 3 if you are struck in a location covered by rigid armor and the final damage would be a level 4 or 5 blunt wound, reduce it to a level 3 blunt wound.
Any time a character manages to suffer a level 4 or 5 wound through their armor, it’s assumed that that location on their armor has been damaged.
For any rigid metal armor, the location is deformed around the wound and once removed that part of the armor can no longer be worn.
Example Armors

(the numbers represent the AVs)
Padded Coif 2
Boiled Leather Cap 2R
Maille Coif 3M
Munitions Plate Open Helm 4MR
Weapon Properties
Crushing: Weapon ignores the rigid quality when striking armor.
Plate Piercing: Weapon ignores the metal quality when delivering piercing damage to plate or maille armor.
Example Weapons
Rondel -1c/0p Close r2 Grappling, Maille Piercing
Greatsword 2c/2p ext r5 2h
Flail 1b/- Medium r2 1.5h Crushing, Flexible
Warhammer 1b, 0p/1b Medium r4 1.5h, Crushing, Hook, Maille Piercing (Thrust), Plate Piercing (Swing)
Halberd 3c, 1p/3p ext r4 2h, Hook, Plate Piercing (Swing)
Quarter Staff 1b/1b long r1 2h

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 09:36
by FortPwnall
So... one suggestion I'd have is to do the following. Have two properties as follows:

"Maille: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage."
"Plate: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage, and then also caps all converted blunt damage at 3 (after subtraction)."

Then something is given only the maille or plate property. Don't give boiled leather this property at all, just make it a tougher version of the leather, i.e., not Maille or Plate, but has AV of 3.

This essentially removes the need for the "crushing" property, since it seems that everything in the weapons table that does bashing damage basically already has crushing, except Bec de Corbin which has plate piercing anyway... ;) and the wooden club, for which you could perhaps specify as a property of the club (i.e., club damage vs plate is capped at 3) if you want.

You then still keep the Maille-piercing and Plate-piercing properties for weapons, and crushing would be a property only of very specific piercing or bashing weapons, which would probably not even be used (because it's better done with "piercing"), but maybe there would be select heavy-headed bladed weapons you might want to give the crushing property (like the pollax). Then spears and swords still don't dent through plate, though I must say: it is surprising what can be done with even an iron age large leaf shape Celtic spear on a 16 gauge / 1.6mm hardened steel 15th century style breast plate, as demonstrated in this video: https://www.youtube.com/watch?v=E8vFfDuG-iA, though still, capping the damage makes sense to me.

Thoughts?

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 10:01
by thirtythr33
Hi, welcome to the boards!
FortPwnall wrote:So, if I'm understanding this correctly, if I slice someone who is wearing a maille coif on the head with a greatsword, all of the slicing damage is converted directly to bashing damage? Whereas if I hit someone wearing a padded coif, it just counts as slicing damage of the same amount?
Correct. Keep in mind you still reduce the damage by the armor amount, so if you got hit by a 5 damage attack the maille coif would reduce it to a level 2 blunt and the padded coif would take a level 3 cutting wound.
FortPwnall wrote:I get that a greatsword can cause some serious blunt force trauma, but is its damage not primarily due to the fact that it is cutting? Should it really be doing the same amount of blunt damage as it would have done cutting damage?
Yes, a lot of the damage comes from the cut. That's why the damage is capped at level 3. And the draw cut maneuver deals additional damage which is negated by the metal armor.
FortPwnall wrote:Does the damage table make up for this? I.e., is a slice-wound more serious than a similar level bash-wound?
Yes, blunt is considerably worse. In general, cutting will give a higher TN modifier and result in bleeding. Here's the level 3 crown wounds for example:

BLUNT:
Impact 6, TN4
Mild concussion. Ears ringing, bad headache and dizziness. Some blood in the hair. KO3

CUTTING
Impact 6, TN5
Flap of loose scalp or deeper cut with skull intact. Dizziness and bleeding. BL1, KO3

Also, the level 5 cutting wounds result in dismemberment. The blunt level 5s can (sometimes) be recovered from.
FortPwnall wrote:But if so, shouldn't bludgeoning weapons be doing more damage in general to compensate?
Why do you think they need it? The damage types have been designed so that generally, Cutting > Piercing > Blunt. They are balanced by the fact that Cutting is the most damaging type but is also the easiest to negate. Blunt is the weakest type but cannot effectively be countered. Piercing straddles between the two in effectiveness and applicability.
FortPwnall wrote:It seems that any bashing weapon worth its salt in the table has the crushing quality anyway, but if I bash you really hard with something that doesn't have this quality, like say I bash you with a quarterstaff on your boiled leather cap, then the damage gets capped? Like, my quarterstaff is incapable of smashing through your cap? I don't know much about boiled leather, but since it is "akin to hard plastic sporting pads" I guess I can understand it being impossible without using a "crushing" weapon?
Correct, a blunt attack without the crushing property is capped at level 3 against rigid armor. As you can see above though, a level 3 blunt wound to the head is enough to force your target to pass a K.O. test or fall unconscious. So your quarter staff could still knock your target out, effectively winning the combat in a single blow. You just can't completely cave their head in like a weapon with Crushing could.
FortPwnall wrote:Furthermore, the rules say that any time a character manages to suffer a level 4 or 5 wound through their armor, it’s assumed that that location on their armor has been damaged. Does the cap get calculated before this rule apply? Does it actually mean it is impossible to damage e.g. metal plate with a quarterstaff or greatsword? This is an entirely believable proposition, to be honest. It also implies it is impossible to damage boiled leather similarly. But the rules as-written don't make it terribly clear.
That's an interesting question. I imagine it will be considered after the wound is reduced but you will have to get Agamemnon or higgins to give the final word on that.
FortPwnall wrote:So... one suggestion I'd have is to do the following. Have two properties as follows:

"Maille: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage."
"Plate: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage, and then also caps all converted blunt damage at 3 (after subtraction)."
Why wouldn't you just increase the AV of all metal armor by 1? It's identical in effect but requires less math.

The full damage formula is Wound Level = Weapon DR + Attack MOS + Attackers BTV - Defenders BTV - Armor AV

All the maille and plate armors are already mitigating more damage than the non metal armors.
FortPwnall wrote:This essentially removes the need for the "crushing" property, since it seems that everything in the weapons table that does bashing damage basically already has crushing, except Bec de Corbin which has plate piercing anyway... and the wooden club, for which you could perhaps specify as a property of the club (i.e., club damage vs plate is capped at 3) if you want.
Most weapons intended for Blunt attacks do get Crushing. The difference comes when you are considering attacks that were originally cutting and are converted to blunt won't ever have crushing. You need some way to delineate between a MOS5 sword attack that is converted to blunt and a MOS5 mace attack. If the mace has crushing, it will deal full damage but the sword will still be capped.



If you dig around in this thread, you will find some more explanations as to why things were designed this way.
viewtopic.php?f=13&t=373

But basically, here's the TLDR version:
Agamemnon wrote:Our rules weren't drawn up in a vacuum. There was an exhaustive amount of research that went into figuring out how the historical bits fit together, particularly where armor and weapons were concerned. I've got a shelf full of books and historical accounts, we have a folder somewhere of pdfs. We've talked to a number of people who are experts on the actual subject in question, whose job is literally studying, recreating, testing, and writing about this stuff. After talking to them, we came to certain conclusions that formed the basis of the rules.

No historical man-sized weapon wielded with man-sized force is going to meaningfully cut into a steel breastplate. At best, you're going to put a decent-sized dent in it. Even against iron, the result is a slightly larger dent. This is a limit imposed by the fact that you are banging tempered iron against tempered iron. Physics doesn't care how much you can bench, you aren't going to produce enough acceleration to make that work.

Piercing plate is extremely difficult short of a weapon whose geometry is explicitly designed to pierce plate. You can usually tell when you see them, because they are generally shaped like railroad spikes. You're talking about something like a spike on a polearm or the beaked end of a warhammer. I've seen plenty of questionable tests in which someone "pierced" a suit of plate armor with a sword. None of these tests that I've seen have disclosed the gauge or type of steel that the pierced armor was made from, and in none of these cases has the blade gone deeply enough into the plate to meaningfully pierce the person through the padding that would have been below. Further, we have plenty of historical accounts of the efficacy of armor, particularly plate. After (I believe it was) Agincourt, there were french knights laying exhausted and helpless in the mud and unable to defend themselves. The soldiers that dispatched them had to pry open their visors and thrust daggers through the knight's eyes because the soldiers were having trouble finding a significant gaps in the plate.

No historical man-sized weapon is going to cut or chop through riveted maille (as was used nigh-universally throughout Europe). You absolutely can bust a few links with a particularly good strike from a particularly heavy weapon, but you aren't going to cut through the maille and through someone's arm beneath it. The breaking links themselves help function the same way modern day ballistic plates do -- the act of breaking the ring helps disperse the force. You'll break the dude's sternum, but you won't bust enough links to make a big enough hole through the maille to push the blade of the weapon through AND then also cut through the padding beneath AND THEN also into their chest beneath it. Like with plate, if you're not piercing it the goal is to deliver blunt trauma through it. Hell, cutting into a historical gambeson isn't a particularly easy task on its own.

Piercing maille is somewhat easier, but still very difficult unless you have a weapon whose geometry is explicitly designed for piercing it. Maille-piercing weapons still aren't "cutting" through maille, they are designed to get into the gaps of rings and burst them. This is why later swords became so drastically tapered and diamond cross-sections became the norm. They needed the sharp point and rigid geometry to help needle their way in and bust the rivets open so the blade can penetrate.

Armor is very, very good at what it does. So good, in fact, that soldiers have been willing to bear the weight, heat, and overwhelming expense of it in one form or another for the fifteen hundred years or so our game can easily cover. The more Higgins and I have researched it, the more HEMA people and historian-types we've talked to, the more the above seems to ring true. There are always outliers and stories about this or that person this one time getting his helmet cut in half by an axe, but we never see evidence of this in the archeology, this isn't what's written in the manuals by people of the period, and never seems to bear out in testing with period-correct materials. I'm perfectly comfortable chalking these outlying cases up to a combination of malfunctioning equipment, bad steel, or just outright hyperbole. The Norse talk about swords that can cut through rocks and trees in a single blow. I've heard rumors about Japanese soldiers cutting through machine-gun barrels, too.

People have been riding their own hype-trains for literally as long as we have been communicating as a species. I am sure if you could go back to the Pleistocene you'll find someone who will brag that their flint-knapped spear was so sharp, their aim so true, and their arm so powerful that they threw it clean through one side of a mastodon and out the other side, felling the beast in a single blow. That man's tribe mates will roll their eyes and give the dude shit for it, but after he dies that'll be the story they tell because it's how they want to remember him.

Are there fringe cases? Sure. But we put a huge amount of resources into modeling the combat as it is. I don't see a benefit in modeling metallurgical impurities, botched tempering, and the effects of entropy on armor. I've run our work past professional academics and active-HEMA types alike. I'm perfectly comfortable going with their stamp of realism. At the end of the day, "playable game" is a higher priority than "detailed simulation of every possible factor."

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 10:28
by FortPwnall
Thank you for your detailed response! I really appreciate it!


thirtythr33 wrote:
FortPwnall wrote:So... one suggestion I'd have is to do the following. Have two properties as follows:

"Maille: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage."
"Plate: Converts all slashing and piercing damage to blunt and subtracts 1 from such converted damage, and then also caps all converted blunt damage at 3 (after subtraction)."
Why wouldn't you just increase the AV of all metal armor by 1? It's identical in effect but requires less math.

The full damage formula is Wound Level = Weapon DR + Attack MOS + Attackers BTV - Defenders BTV - Armor AV

All the maille and plate armors are already mitigating more damage than the non metal armors.
FortPwnall wrote:This essentially removes the need for the "crushing" property, since it seems that everything in the weapons table that does bashing damage basically already has crushing, except Bec de Corbin which has plate piercing anyway... and the wooden club, for which you could perhaps specify as a property of the club (i.e., club damage vs plate is capped at 3) if you want.
Most weapons intended for Blunt attacks do get Crushing. The difference comes when you are considering attacks that were originally cutting and are converted to blunt won't ever have crushing. You need some way to delineate between a MOS5 sword attack that is converted to blunt and a MOS5 mace attack. If the mace has crushing, it will deal full damage but the sword will still be capped.
One of us isn't understanding the other one correctly here. What I was suggesting is that metal armor gets equivalent of +1 vs sharp but not vs blunt.

Let's say opponent has maille armor with AV of 3 and you do 4 damage with a sword. Under current rules then you would convert to blunt, and subtract 3, and get 1 damage. If you did 4 damage with mace, same thing, and you do 1 blunt damage.

Now I was saying, what if instead if you did 4 damage with sword, you convert to blunt, and then subtract an extra point, dealing 0 blunt damage, but if you do 4 damage with a mace, you don't subtract the 1 damage. This represents the fact that a lot of the damage via a sword is due to the bladed property. This is not the same as just adding 1 to AV, because I only subtract 1 from the converted damage, not normal blunt damage.

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 10:31
by FortPwnall
But yes, I do understand your general points, and the system as it stands does seem well-designed once I've understood it and given it some thought.

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 10:42
by thirtythr33
FortPwnall wrote:Let's say opponent has maille armor with AV of 3 and you do 4 damage with a sword. Under current rules then you would convert to blunt, and subtract 3, and get 1 damage. If you did 4 damage with mace, same thing, and you do 1 blunt damage.

Now I was saying, what if instead if you did 4 damage with sword, you convert to blunt, and then subtract an extra point, dealing 0 blunt damage, but if you do 4 damage with a mace, you don't subtract the 1 damage. This represents the fact that a lot of the damage via a sword is due to the bladed property. This is not the same as just adding 1 to AV, because I only subtract 1 from the converted damage, not normal blunt damage.
Since MOS is uncapped, this would still result in some strange effects. For example, if I got 10 MOS with my dagger I would be able to cave in plate armor. The cap is effective because it allows you to use a sword to easily shake or bruise someone in plate on a moderately successful attack, but also keeps it impossible to really cave the plate in and kill them on a hugely successful attack.

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 11:07
by Agamemnon
thirtythr33 wrote:
FortPwnall wrote:Does the damage table make up for this? I.e., is a slice-wound more serious than a similar level bash-wound?
Yes, blunt is considerably worse. In general, cutting will give a higher TN modifier and result in bleeding. Here's the level 3 crown wounds for example:

BLUNT:
Impact 6, TN4
Mild concussion. Ears ringing, bad headache and dizziness. Some blood in the hair. KO3

CUTTING
Impact 6, TN5
Flap of loose scalp or deeper cut with skull intact. Dizziness and bleeding. BL1, KO3

Also, the level 5 cutting wounds result in dismemberment. The blunt level 5s can (sometimes) be recovered from.
FortPwnall wrote:But if so, shouldn't bludgeoning weapons be doing more damage in general to compensate?
Why do you think they need it? The damage types have been designed so that generally, Cutting > Piercing > Blunt. They are balanced by the fact that Cutting is the most damaging type but is also the easiest to negate. Blunt is the weakest type but cannot effectively be countered. Piercing straddles between the two in effectiveness and applicability.
If you look at historical fighting, this bears out. With the exception of late rapiers, nearly all weapons meant for fighting lightly or unarmored opponents relied on big slashing wounds. The most effective way to stop an opponent is with a slashing weapon, generally. Even when they aren't fatal, they tend to be more immediately incapacitating, traumatic, and bleed more. Piercing weapons are next in line, but have the problem that while you can pretty easily put a hole in someone, you have to be very particular about where you put that hole in order to stop them fast enough that they can't also put a hole in you. Blunt trauma is generally the most forgiving of all. In a medieval context, bone-setting is easy to do but if you had to sew someone up (as from a cutting or piercing wound) they might take infection and die. The only time you're going to die from a blunt injury is if you took it to the head or chest.
thirtythr33 wrote:
FortPwnall wrote:Furthermore, the rules say that any time a character manages to suffer a level 4 or 5 wound through their armor, it’s assumed that that location on their armor has been damaged. Does the cap get calculated before this rule apply? Does it actually mean it is impossible to damage e.g. metal plate with a quarterstaff or greatsword? This is an entirely believable proposition, to be honest. It also implies it is impossible to damage boiled leather similarly. But the rules as-written don't make it terribly clear.
That's an interesting question. I imagine it will be considered after the wound is reduced but you will have to get Agamemnon or higgins to give the final word on that.
Correct. I can't actually inflict a level 4 wound on plate with a sword, therefore I cannot damage plate with a sword - at least not to an extent that is mechanically significant. Narratively, one can assume there are scratches and dents some poor squire will have to tend to.

Boiled leather is an interesting case because it's actually quite good if you have legitimate boiled leather. The rub is that if you hit it with a quarterstaff or something, it will bounce more than it will crush. On the other hand, Rigid only applies to blunt wounds. If you hit it with a sword you'll still cut through it. The only time it gets a little weird is when someone is wearing boiled leather over maille, as it essentially becomes a poor man's coat of plate-- but historically, that's the only use for it we could verify to any degree, so that sounds about right.

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 12:02
by FortPwnall
thirtythr33 wrote:
FortPwnall wrote:Let's say opponent has maille armor with AV of 3 and you do 4 damage with a sword. Under current rules then you would convert to blunt, and subtract 3, and get 1 damage. If you did 4 damage with mace, same thing, and you do 1 blunt damage.

Now I was saying, what if instead if you did 4 damage with sword, you convert to blunt, and then subtract an extra point, dealing 0 blunt damage, but if you do 4 damage with a mace, you don't subtract the 1 damage. This represents the fact that a lot of the damage via a sword is due to the bladed property. This is not the same as just adding 1 to AV, because I only subtract 1 from the converted damage, not normal blunt damage.
Since MOS is uncapped, this would still result in some strange effects. For example, if I got 10 MOS with my dagger I would be able to cave in plate armor. The cap is effective because it allows you to use a sword to easily shake or bruise someone in plate on a moderately successful attack, but also keeps it impossible to really cave the plate in and kill them on a hugely successful attack.
I wasn't suggesting removing the cap for blades. Sorry if that was unclear. I was focusing just on the damage subtraction part.

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 12:21
by nemedeus
Agamemnon wrote:The only time it gets a little weird is when someone is wearing boiled leather over maille, as it essentially becomes a poor man's coat of plate
Don't you mean maille over boiled leather?

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 12:27
by thirtythr33
nemedeus wrote:Don't you mean maille over boiled leather?
Usually, but then there are these guys who wear gambeson and jackchains over maille. So who really knows?
Image
Image
Image
Image

Re: Questions: Armor Rules

Posted: 06 Sep 2017, 12:53
by Agamemnon
nemedeus wrote:
Agamemnon wrote:The only time it gets a little weird is when someone is wearing boiled leather over maille, as it essentially becomes a poor man's coat of plate
Don't you mean maille over boiled leather?
Not insofar as I can tell. When you think boiled leather, think "prototype plate" or "poor man's plate." Every discussion of the thing I've come across suggested they were wearing bits of cuir bouilli over their maille in the way people would later wear plate over maille and in the same kinds of pieces. The only surviving piece of which I'm aware is this, which was worn on the upper arm:
Image

We see something that appears to be similar depicted on this man's arm as well:
Image

How common this stuff was is up for debate, but we get little hints at it being used for greaves, vambraces, or elbow/knee cops. I've seen less substantiated sources claim there is some evidence for breast/back plates made of it (notably the word cuirass and cuir bouilli share a similar root) but I don't have enough sources to make a definitive claim. This is one of those subjects that, short of some insanely well preserved bog find, I don't think anyone will ever reach a historical consensus on. We chose to err on the side of caution in making it available.

Re: Questions: Armor Rules

Posted: 07 Sep 2017, 05:40
by Benedict
I think that thirtythr33 and Agamemnon covered most points. The one that is left out is Maneuver effects.

For example Murder Stroke gained the Crushing property in 'Bastards, breaking the Cap against Rigid helmets, thus making Lv5 Blunt trauma pretty viable against plate armor. :twisted:

That been said, and bearing in mind the fact that Maneuvers are getting an overhaul, I'm withholding any criticism and praise until we get the whole picture. ;)

Re: Questions: Armor Rules

Posted: 08 Sep 2017, 14:48
by nemedeus
thirtythr33 wrote:
nemedeus wrote:Don't you mean maille over boiled leather?
Usually, but then there are these guys who wear gambeson and jackchains over maille. So who really knows?
iirc the going theory for these depictions in particular were either a mistake on the artist's part (not like that's something that doesn't happen today, so it would make sense to assume the same of earlier periods) or that the thing worn atop the maille was something else and the depictions are misleading. i think we should be able to agree that wearing maille under non-plate armour is not only very much less effective, but also it may even make the maille a hazard in itself.

Re: Questions: Armor Rules

Posted: 08 Sep 2017, 16:09
by Agamemnon
nemedeus wrote:
thirtythr33 wrote:
nemedeus wrote:Don't you mean maille over boiled leather?
Usually, but then there are these guys who wear gambeson and jackchains over maille. So who really knows?
iirc the going theory for these depictions in particular were either a mistake on the artist's part (not like that's something that doesn't happen today, so it would make sense to assume the same of earlier periods) or that the thing worn atop the maille was something else and the depictions are misleading. i think we should be able to agree that wearing maille under non-plate armour is not only very much less effective, but also it may even make the maille a hazard in itself.
Except we have at least one extent piece, an image of which I linked, and one of the main reasons people argue that there are depictures of cuir bouilli is that they are richly decorated and engraved and thus probably not actual metal armor which was much, much less engraved in the periods we are discussing. If it was worn exclusively under maille armor, then A) it wouldn't be so richly ornamented and B) we wouldn't know that they were wearing it anyway because it would be depicted as just maille.

I've heard from credible sources arguments that it existed and was probably more common than we think, I've heard arguments from credible sources that it existed but was probably rare, I've heard arguments from credible sources that it probably never really existed aside from a couple odd examples that people tried and quickly abandoned. I'm not sure we can call any of this a "going theory," and I doubt any consensus will be reached any time soon.

Cuir Bouilli isn't even the only non-plate armor allegedly worn over maille. We know gamboised cuisses were generally worn over chausses. You'd have a bit of woolen hose, the maille chausses, and then over it the gamboised cuisses- possibly with a poleyn or knee cop. We also have some evidence of people wearing thick gambesons over maille, and later it became somewhat common to wear jupons over plate, even.

In any case, we can't say with any real historical certainty, which is why the rules don't prescribe it one way or the other.