This is a blackjack. I'm not sure if it's a weapon or some sort of BDSM sex toy. Blackjacks should be replaced with something historical Jesters actually used, a marotte.
A marotte is a prop stick or sceptre with a carved head on it. The word is borrowed from the French, where it signifies either a fool's (literal) "bauble", or a fad/craze. Typically carried by a jester or harlequin, the miniature head will often reflect the costume of the jester who carries it.