The Jutte is a law enforcement weapon from the Edo Period.
The literal meaning of Jutte translates into "Ten Hands". It's normal length can extend to about 18 inches(45 cm). It was originally used during law enforcement of the Edo period in Japan. Current uses is far more commonly through martial arts practices.
As a weapon is could be used as a hand held club. The popular misconception of the Jutte is that it is used to capture a sword. While it is possible, the actually size of the tool makes that a risky endeavor. The hook, or tine, is used primarily to hook and strike at the joints of the body.
It first appeared in One Piece Volume 12 One Piece anime episode 48. The tool went primarily unused in the Loguetown Arc. During his fight with Luffy, Smoker was winning easily. He was about to pull the jutte, but was stopped by the Revolutionary, Dragon. A powerful wind began to blow, and Luffy was able to escape.
During the massive battle against the Marines and Whitebeard Pirates, Smoker once again almost captured Luffy using his jutte, but he was saved by Boa Hancock. She used a powerful kick and shattered his weapon.
In the One Piece series holiday episodes, One Piece Jidaigeki Special, the characters are put into a fictional nation that is very similar to the Edo period of Japan. In this world Luffy is a law enforcement officer called Luffy Oyabun. He still has his trademark straw hat, but now used a jutte in combat. Not as a tool of martial arts, but more as a simple club to go along with his regular fighting style.