Webyushiro was able to get control of um4 and his control over her was strong enough that muzan had no choice but to kill her as he was unable to regain control.
Webyushiro impressively was able to fight muzan absorbing his cells through nakime, thus implying yushiro manipulates his victims on a celluar level.
Yushiro requires to be in.
Demon slayer corps blindfold is yushiro’s blood demon art, which allows one to do either of two.