Unknownreported this bug
Summary
On mythic items AND/OR mythic enchants, if the item uses some sort of skill to deal damage (such as a projectile skill), it will not trigger ~onKill triggers. In addition, if the item is a book/enchanted book, it wont either. (I use enchanted books as spell tomes for my server)
Usage
the ~onKill skills of every item a player is holding/wearing should be run when the player kills something.
Value
~onKill triggers do not work as expected when using projectiles. This should fix it.