It doesn't seem like Zoro's other sword can hurt Kaido. They are mostly cautious of Enma thus far due to the strange Haki eminating from it
With that said I think Zoro might gradually upgrade his haki during the fight to show he is worthy of the blade and allowing him to hurt Kaido with all his blades
With that said I think Zoro might gradually upgrade his haki during the fight to show he is worthy of the blade and allowing him to hurt Kaido with all his blades
He already hurt Kaido with all his Swords