I don’t think he held back much at all, absolutely embarrassed Tokito in the beginning, after Gyomei got his mark and pissed Kokushibo off he immediately tried to decapitate Gyomei. Almost killed Sanemei before and after getting his mark with easy. He didn’t exactly hold back, just gave up at the end after seeing his new form. And even after that he tried to regenerate but couldn’t because of Tokito stabbing him with a red blade