A Barguest in the RQ2 Gateway Bestiary had the ability to cause 1D8 CON damage to anyone who strikes it with a physical weapon.
I have reworded it to the following:
I am not sure about the name "Damaging Wound" - does anyone have any suggestions as to a better name for the Trait.Damaging Wound (Damage)
Anyone striking the creature with a physical melee weapon takes the stated damage. If the damage is to a characteristic then the attacker loses the stated number of points of that characteristic. If the damage is to hit points then the attacker takes the damage to the hit location, or locations, that are holding the melee weapon, or the physical location used if the melee weapon is a natural weapon.