Board Thread:Off Topic/@comment-25857155-20150111054847/@comment-25857155-20150213015346

That's the idea. The drawback being that to power himself up, he has to cut himself and use his own blood unless he can draw blood from his opponent. Also, he does not use Grimm blood, since the effect might be unpredictable. In other words, in a long fight with someone too quick for him to cut, he would have to bleed himself to keep powered up, which would eventually backfire.