@Kanol That wouldn't change much.
As he pointed out himself, physical attacks does deal damage, but the slime Regen is so strong that he instantly heals.
@Asta He can also apply DoT effects like burn or poison to impede it's regeneration. There's also systems of damage where some damage types deal more persistent damage. Chop a slime up into a thousand pieces and the slime's still there in a thousand little 1 hp chunks. Burn a chunk of it and that chunk is gone. So like a HP down that reduces a target's max HP rather than recoverable damage. Point is, I wouldn't be trying to slash apart a slime that walked up as two separated blobs.
hmm but his claws weren't able to cut him up and he doesn't have anything that reduces max hp nor does he know if such a thing exists. If he relies on DoT, it would have to be something so effective that it could match near instant recovery. If he could do that and keep attacking that would work but I don't think he can now.