Number 5 best swordman in one piece

Roronoa Zoro: Zoro is an extremely powerful master swordsman, being able to use one, two, and three swords in varying attack styles. He is even able to use Flying Slash Attack, a high level sword technique that utilizes the very air pressure of sword swings itself to strike the enemy from a distance. Since no one else has been seen using anything similar to his Santoryu style, it can be assumed that Zoro invented not only Santoryu but most, if not all, of his sword techniques. After his two years of training Zoro is now able to easily cut through materials even stronger than steel. He also learned how to imbue his swords with Haki.