Issue is also open here: https://github.com/CleverRaven/Cataclysm-DDA/issues/18177
First, Mugling apparently shifted the knife function from a use_action to either cutting or butchering quality, and it doesn’t play well with active items. Simply removing the crafting qualities from active athames will solve that.
Hammer of the hunter, veinreaver, and cursed sword all generate an error message on activation. Giving their active versions their respective essence as an ammo type, then adding the flags NO_UNLOAD and NO_RELOAD, will unfuck all three.
However, the hammer of the hunter can also be resolved by simply setting target_charges to 0 in the inactive version’s use_action, doing the same with the initial_charges of the active version. This also eliminates an unintended turn of excess delay between activation and flashing.
Everything beyond that is just old, lingering typos on my part.