My point is that he can't put the same amount of haki on shisui
Enma isnt just a blade, it's curse allows zoro to release more haki
Enma isnt just a blade, it's curse allows zoro to release more haki
Of course the gradding of the sword is important as it boosts the power accordingly, but current enma and Shusui are the same grade and thus almost equaly as powerfull, Shusui might even be a bit better since it is a black blade whos grade was raised by Ryuma, but Enma has a higher potential since Shisui already reached the limit of how good it can get.