@LANJI CUCKSMOKE don't misunderstand me, the point I'm making is Shanks' Swordsmanship is basically Roger's own but just with one less arm.
It might very well be something like
Roger = 2 Armed Shanks (his full potential) >~ Mihawk >~ 1 Armed Shanks (when he sacrificed his potential/arm for Luffy).
Just posting this before you misinterpret my post into something it wasn't meant to be.