Imo there should be gaps. Swords make swordsman stronger so better swords should mean better swordsman. Imo id say if a swordman is 100% with a supreme grade sword then they should lose about 5% every grade they go down. So if they go from supreme grade to a normal sword it should be about a 20% decrease in power. Swords are important but overall other abilities far out class just the sword in op. So pretty much in the case of mihawk with yoru vs mihawk with a normal sword then yoru mihawk should high diff normal sword mihawk as he should get decently weaker.