He is a member of the so-called Seven Warriors of the Sea and is also the current holder of the title of being the Best Swordsman in the World. He was the one who trained Roronoa Zoro during the timeskip.
His sword is "Kokutō Yoru", one of the 12 Supreme Swords, it is a black blade sword with double irregular pattern, ornate and ornate, with a hilt that resembles a cross and finished in a long shiny edge.