I'm still loving this game more than any other OSR game these days. I love everything about it.

But I'm struggling with how to represent a character wearing, say, only the breastplate/cuirass of his suit of plate armour, or any stripped-down, half-suit of any of the armours presented in the core book. I've never been big on "homebrewing" my own rules.

Is this addressed in any of the supplementary books?  If not, I'm open to suggestions, or even a ruling from the man himself. 

I'd rule that the AC is equal to the Armor worn. With that being said, using the rules for called shots would treat the areas without armor as having no Armor. So, smart combatants would target limbs, etc to disable the opponent, before moving in for a kill.

Quote from: SteelClad_Lad on February 16, 2023, 02:31:56 PM
But I'm struggling with how to represent a character wearing, say, only the breastplate/cuirass of his suit of plate armour, or any stripped-down, half-suit of any of the armours presented in the core book. I've never been big on "homebrewing" my own rules.

Is this addressed in any of the supplementary books?  If not, I'm open to suggestions, or even a ruling from the man himself.

Not to my knowledge, except for this note:

Quote from: Lion_&_Dragon,_page_67
Note: All armors are presumed to come with a helmet; a metal «sallet» in most cases, or a helm with plate. If for some reason the helmet is not worn, the AC is reduced by –1.

Soif you take off part of a harness (in this case, the helmet) the AC bonus of the armour falls. So it stands to reason that if other parts are missing, AC should fall further. How much, though?

The rule of nines is used by emergency trauma care professionals to estimate how much of the surface of a body has been affected by a burn. It goes like this:

• head: 9%
• left arm: 9%
• right arm: 9%
• upper torso: 18%
• lower torso: 18%
• crotch: 1%
• left leg: 18%
• right leg: 18%

So I'd compute how much of the body is armoured and apply that factor to the AC bonus. For example, a cuirass covers the upper torso, the lower torso, and the crotch, so 37% of the body. Full-body Plate & Hauberk gives an AC 16 (18), or +6 (+7) above unarmoured. 37.5% is 3/8, so just the cuirass is +2.25 (+2.625) above unarmoured, which afrer rounding gives AC 12 (14). The DEX and init penalties are similarly rounded, so in this case it would be -1 init, -2 DEX skills.