True swordsmans put everything they have behind their swords, Roger and Shanks must have Haki abilities that are not related to swordsmanship.. Roger and Shanks use swords as a weapon while Mihawk and Zoro use their swords as a way of life.. Example Roger isn’t the type of swordsman to care about making dents in his sword unlike Mihawk who counts every nick as a mark of shame..
Didn't care about his sword my ass.