The world of One Piece contains some exceptionally powerful sword-wielders. As soon as Pirate Hunter Roronoa Zoro joins the Straw Hat Pirates, swordsmanship becomes a major part of the long-running series. Each arc, One Piece's protagonists encounter new swordsmen who can perform incredible feats thanks to a mix of Haki and Devil Fruit-related powers.
Source：https://www.cbr.com/one-piece-strongest-swordsmen/
