Nanashaku Jitte

Marine Commodore Smoker carries a jutte with him as his primary weapon. The tip of the stick is made of Seastone, which Smoker uses to suppress Devil Fruit users' powers in order to capture them. The weapon was effortlessly destroyed when Boa Hancock kicked it after its petrification, causing it to crumble in pieces.

Abilities
As the jutte is tipped with Seastone, it can be used to nullify Devil Fruit powers simply by contact. Smoker uses this to his advantage to strike such opponents, as well as to stop them by sapping them of their powers and mobility. He uses it in conjuncture with his Moku Moku no Mi powers to get close to his opponents in order to make his strike land.

As the jutte is partly made of seastone, it does not transform into smoke along with Smoker.

Trivia

 * The jutte is a weapon used by Japanese law enforcers, which fits Smoker's status as a Marine officer perfectly.