Right now as we all know, The Blackbeard Pirates are hunting devil fruit users to strengthen their power.
One of the possible devil fruit hunt by the Blackbeard Pirates is the one currently owned by Diamond Jozu. The diamond devil fruit.
The most worthy of using this power would be Shiliew of the Rain. The swordsman in Blackbeard Pirates.
Diamond is one of the hardest material in the world, This is the perfect devil fruit to be held by swordsman, If it were to be clad with armament haki, it would make it seems impossible for anyone to penatrate or cut.
Perhaps Shiliew will defeat Mihawk to own the title of strongest swordsman, And the final fight would be Zoro versus Shiliew, By defeating and penetrating or cutting through the armor would make Zoro the strongest and the first swordsman to ever cut diamond.
Of course I might be wrong, I’m not Goda after all.
*Theory by SoulKing