This story was already being ruined by Yuuto being so damn passive, yet now the author decided that surely he's not passive enough yet, so let's give him a power that prevents him from going all out. Of course he never went all out in the first place because he doesn't really care about anything enough to bother to put in serious effort. Even after all this, getting tricked to absorb that skill 100% according to the human noble's plan, Yuuto is just stupidly standing there, not even really saying anything. It would be cool if he actually knew what he was doing and thus knew the berserk skill won't have any negative effects on him, but of course he knew nothing of that sort. His lithium brain just doesn't allow him to get angry, not even slightly annoyed.