Eric

Erik the Whirlwind is a powerful mercenary. Wielding the power of the Kama Kama no Mi (カマカマの実), Erik is able to use his lengthened fingernails to cut through the very air to create razor-sharp gusts of varying size. He was sent by the Marines, namely by Commodore Nelson, to capture the famed Thousand-Year Dragon, a creature with rumored medicinal value. Erik proves himself to be a dangerous opponent when ultimately facing Luffy, inflicting multiple wounds against his opponent, but he proves to be no match for the Straw Hat captain.

His part in the storyline is short, but rather humorous. Playing innocently on Erik's power (Kama-Kama), Luffy often frustrates him by calling him "Okama" (homosexual or transvestite) during battle. In the end, Erik is defeated not by Luffy, who gave him a rather smart battle, but by Nami as well; just as the crew began to climb the Reverse Mountain, leading to the infamous Grand Line, Erik reappeared to obtain his revenge, but found himself tipped over the edge of the Going Merry and into the water by the wily thief before a battle could erupt. He is most-likely dead, due to the negative side-effect of his Devil Fruit.

Trivia

 * This Devil Fruit gives Erik power similar to CP9's Rokushiki move Rankyaku but, as Erik is a filler character, it is unknown which is stronger. Erik's abilities comes from a Devil Fruit power, but the Rokushiki moves are of Super-Human Strength. Luffy was able to withstand Erik's attack with ease, while he recoils after being hit with Rankyaku.