User blog comment:Marco the Marine Admiral/Theory: Evilness Can Lead to Power-up for Dragon Slayers/@comment-4829046-20140628162149

In addressing to the concept though. It is true that emotion should feed DS power-ups along with necessary elements but saying "evil" is a different story. It could merely be the boiling rage or perhaps the battle-maniac instinct within them. Maybe that thrill of destruction needs to arise for DS magic to really kick in.