I just remember a post from Rap on the steam forums. I couldn’t find it anymore though.
There has to be a minimum of 15 HP damage to inflict a wound. This will get reduced by crippling strikes. Then it is also depending on the maximum HP of the brother if I am not mistaken.
The type of wound inflicted depends on how much damage (% of max HP) a brother takes – a heavy hit will inflict a more devastating wound than f.e. a hit from a light crossbow.
Lastly, different weapons inflict different kinds of wounds. Warhammers/maces will inflict crushing injuries – crushed finger etc.
Piercing weapons (Xbows, Pikes, Spears, Bows, Daggers) will inflict piercing wounds like Pierced Side, Pierced Leg Muscles etc.
I believe Axes, Billhooks, Cleavers have wounds like Split Shoulder, Split Hand.
I’m not sure what kind of wounds swords inflict, but I believe they are in the same category as Axes and Cleavers.
I’m also not sure if chance even plays a role in this or if its just based off HP values. Orc Warriors and Hedge Knights have huge HP pools so I think 15 damage won’t be enough damage to cause a wound in general.