Powers & Abilities What attack should have Kidd done??

He can't pierce Big Mom's skin, he is dealing damage via the blunt impacts rn, so this attack won't solve anything since it seems author is not applying logic for this (piercing power of the same mass concentrated on a smaller area > piercing power of the same mass concentrated in a larger area), or either Kidd is too stupid to think about this strategy.
Anyway, Big Mom skin hardness lives up to its reputation unlike with a certain drunkard, so even that shouldnt work even if Oda applies here that logic.
If he can damage her enough eventually she will still get cut