User blog comment:BurningHype/RWBY/Soul Eater Crossover - FWMA/@comment-8182065-20150619090513/@comment-24012109-20150619164507

Impossible. Well, not entirely impossible. First of all, the idea is redundant- The whole point of a Meister is to make a Death Scythe-tier weapon for Death, and that requires a Witch's Soul. The Witch/Wizards would need to kill another Witch which would pretty much land him/her right at Public Enemy status. And plus, naturally, Meisters & Witches are at a grudge.

Though, from what I research, it is possible, but it would forsake the witch's powers with a Demon Weapon- Pretty much just making them an opposite aligned Meister.