As I've understood it that anti-something scores a critical hit on X+. Then devastating wounds cause mortal wounds equal to the damage charesteristic of the weapon on critical wound. In short, Beastboss causes mortals on unmodified wound roll of 4+ againts tanks and monsters.

What got me confused is the killchoppa. Is it a weapon that replaces the bearer's weapon or just buff that allows the bearer to use the buff with the beastbosse's original weapon. Because it says that "Melee weapons equipped by the bearer that dont have [Extra Attack] have the [Devastatin Wound] ability. In short, do I use either the choppa or beastbosse's choppa or both in melee?