Navy_King
I think Azuma should learn Sage Art. I thinks Its necessary for the future fights or maybe it will be not necessary. Although I think he can pretty much handle all the Akatsuki members but maybe he will have a hard time fighting Madara(Sage of Six Path) and Kaguya and other Otsutsuki or maybe he handle everyone already since he can just use Haki along with his swordfighting and other jutsus. But then again last time that Author made a fic about Naruto and a swordsman was his Template with Shanks and ichigo i think? And Mihawk and Shanks was rival when it comes to swordfighting and hakis. Although Mihawks haki’s was not much been covered by the canon story but here we can pretty much assume that Azuma here is already strong and can already fight up to the level of sage of six path or up until Otsutsuki.