Board Thread:General Discussion/@comment-31283382-20150220205331/@comment-4906037-20150305191552

Maybe those markings are like Busoshoku Haki from One Piece; they only appear when the Blut is highly focused. I'm saying this because I assume that one can improve their control over Blut through training. Well, of course, instead of shielding the user, it enhances their attack.