Kid possesses a Devil Fruit power connected to magnetism. This manifests in two different abilities, both depicting repulsion and attraction of metals within his vicinity to be used as weapons. The first allows him to repel metallic objects away from himself, such as reflecting a Marine cannonball back towards its shooter. The second ability allows him to draw metallic objects towards him and form them into objects, his most frequent use of this being to form a giant arm made of hundreds of metallic weapons and objects and connecting it to his right hand.
When forming this metallic arm, he can use it to punch his opponents, or as a makeshift shield to block even a Pacifista’s laser beams. It is unknown if the firearms connected to his metal arm can fire at his will or not. In the anime and Unlimited Cruise game, Kid can also launch compressed bullets of scrap metal at his opponent at high speed.
When using his Devil Fruit ability, purple electrical sparks emit from his hands, so his ability may resemble an electromagnet.
The main weakness of the fruit seems to be its dependence from the surrounding environment, which must contain metal in order for the fruit’s powers to be used (though this weakness has yet to be exploited). Other than that, it is also weak against the standard Devil Fruit weaknesses.