During Zoro's fight with King, he made a lot of compromise with him. I know it seems faulty to say King may have been too honorable but in a pirate fight there are no rules. If the opponent refuses to let you die by the sword what are you to do? In the correct circumstance I would say even Ussop can beat Zoro. Let's say we have an Ussop vs Zoro situation. If he had explosive ammo and distance, what is zoro going to do?