I don't get this concept in anime at all. By using the same thing that is troubling them, they fight against the evil. Like yoma in Claymore. Monsters in Owari no seraph and so on. There are many anime like that. In fact, the same concept applies to Tokyo Ghoul as well.
Well I think of it as poison, as it's a cursed power in everyway.i do believe what you said, would be the right term but to each her own.
I don't like meaningless battles like in claymore.
