In the Japanese martial arts the stick is an important training tool- bo (6 foot), jo (5 foot) and hanbo (3 feet) are all explored with unique training lessons.
A subset of these lessons is found in the shinobi zue: the “hidden” stick.
In this set of skills the martial artists uses the movement and kata (forms) of the stick combined with a specialized training tool.
The shinobi zue has many forms and designs- but all are “hidden”.
The stick could be hollowed out at one and and filled with lead to make it a hidden club.
Chains, hooks, and other implements could be added to the inside- ready to “spring” out offering greater distance and timing.
The shinobi zue was used as a hidden training tool for those who think they are familiar in facing the stick- a way to create an opening in movement, or to take away movement in that moment.