In Apocalypse the fights aren't to the death though you can kill. You just need to incapacitate the opponent. Not to mention it was shown that the gods medical stuff is ridiculous regrowing Shiva's arms.
A few chapters ago Izu the oni male that helped teach Kikuru said he could get his broken mana lines repaired temporarily if he basically drowned in a massive amount of it.
NANI!? I mean yeah she knew so much and being an assassin isn't a bad excuse but knowledge about sayings for the world Kaito came from should've been more obvious