Though not a primary weapon of the Ninja, nunchakus (also known as "nunchucks") were used because they could be adapted for many situations. Aside from being easy to carry, the nunchakus were used to defend against most any weapon from a bo to a sword. By trapping the blade of a sword with the chain between the two sticks, a Ninja could entangle and disarm a sword-weilding attacker.


Nunchakus definition by Urban Dictionary