One way to achieve this is having the death script of the mob run a check on the weapon the player has equipped, doing a check directly on the widget can prove useful, add a string value to each weapon holding the animation that would play on death, fr exoample "death_animation" with a value of "decapitate".
The rough script would be something like this (this is just the framework) having in mind that the death script for characters have this built in variables
self - Character who died
initiator - Character who killed the 'self' entity
if widget["equipment_widget_id"].element["weapon_slot_element_id"].item.property["death_animation"] != null then
play_animation(self, widget["equipment_widget_id"].element["weapon_slot_element_id"].item.property["death_animation"]);
else
play_animation(self, "death");
end;
This code references directly the custom property added to the item weapon
and we add a simple check to make sure the value isn't empty, if it is, the normal death animation would play.
Just replace "EQUIPMENT" and "WEAPON" for the corresponding id's, the default would be
widget["equipment"].element["0006"].item.property["death_animation"]
Remember this is just rough code but I'd love to help you out to make that system work!
