A chigiriki is, basically, a Japanese mace. It is composed of a two-foot wooden pole, with a two to two and a half foot long chain attached to it, and a spiked ball attached to the end of the chain. A common use of a chigiriki is to trip one's opponent, using the spiked ball on a chain, and then disable them, by striking them with the pole portion of the weapon. The chigiriki can currently be seen in use in various Araki-ryu traditions. Araki-ryu is a school of fighting that was founded by Minamoto Hidetsuna after the Japanese-Korean War (1592 - 1598). There is curriculum for torite kogusoku (fighting hand to hand), tojutsu (knife and sword fencing), nagamaki-jutsu (fencing with halberds), kusarigama-jutsu (fencing with chained sickles), and chigiriki-jutsu (fencing with chigiriki), within the Araki-ryu school.
Sources Used:
http://homepage.ntlworld.com/mahoutsukai/archive/chainreaction.htm