@LANJI CUCKSMOKE don't misunderstand me, the point I'm making is Saint Shanks' Swordsmanship is basically Roger's own but just with one less arm.
It might very well be something like
Roger = 2 Armed Saint Shanks (his full potential) >~ Mihawk >~ 1 Armed Saint 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.