too bad the author said shanks is a swordsmen
Literally you guys can't even process my words.
Mihawk has the WSS title and yet we know from the same canon that it was ever implied either person won or lost their duels. It wasn't until Shanks lost his arm that Mihawk stopped fighting him out of pity, yet we have no idea if that is purely an underestimation of Shanks' ability as a result. On top of this, you have to even assume Shanks aimed to be the WSS, as if Big Mom or Fujitora or any other top level sword user does outside of a proclamation.
I'm also on the boat that Shanks, while he does fight with a Sword, can only fight with a sword. The only reason I say this is because there are indications Luffy and him may clash in the future (as Luffy has mentioned several times and Shanks excitement to meet him again with a very competitive looking face)
. Again, not purely set in stone, but even if he's a full, pure, run of the mill swordsman, you have to assume he wanted to be WSS, lost to Mihawk, or can't fight Mihawk equally now. None of the 3 have ever been stated or proven in the story.