*looks around* erm anyway
The Chai has a long history found in India, China. Malaysia, and Indonesia; the weapon also migrated to Okinawa where it was pronounced as "SAI" based on its Greek symbol shape.
The jitte’s origins are unclear: Okinawan and Japanese provenance are both claimed. Whatever its origins, this weapon gave rise to a sophisticated method of combat known in Japan as jittejutsu. Its techniques included parries, blows and thrusts, and on occasion the weapon was hurled. The hilt of the jitte could also be used with devastating effect in delivering reverse blows to maim or even kill an unwary opponent.
Mastery of jittejutsu depended upon skill in the art of displacement, called tai-sabaki (body movement), which made it possible for an expert to change positions quickly, sliding or whirling away from an opponent, whose reach normally extended to the tip of his long sword. Since the techniques of kenjutsu (art of the sword) are numerous, the techniques of jittejutsu of necessity had to be sufficiently inclusive to cover all threatening contingencies.
Official use of the jitte was restricted to police officers of the feudal era, for whom it was a symbol of position. Warriors were said to have dutifully acknowledged the efficiency of this instrument, which, in the hands of experts, could snap a steel blade, or send it whirling away. The techniques utilised could be credited with the modern self-defence weapon the Kobutan
Some more info on those weapons.