Two sai

For other meanings of the word 'sai', see Sai (disambiguation).

A sai was incorrectly believed to be an Okinawan tool to measure stalks, or some even say as a pin to hold cart wheels in place, but is better and more correctly known as a weapon. Its basic form is that of an unsharpened dagger, but it also has two long, unsharpened projections (tsuba) attached to the handle.

The sai's distinctive shape makes it a versatile weapon. With skill, it can be used effectively against a long sword by trapping the sword's blade between the sai's blade and the tsuba and breaking it with a twist of the hand. Also, it can be held so that the middle arm fits between the ring and middle fingers, and used as a longer variant of brass knuckles (this stance is only accepted in American styles). Sai come in two traditional styles, one is just rounded arms, still no point at the tip; or what are called octagon sai, which have an octagonal shape on the middle arm.

Traditionally, sai were carried in threes, two at the side, as primary weapons, and a third tucked behind, in case one was disarmed. An alternative use of the third sai is as a throwing weapon to disarm or distract an opponent before engaging in close combat. The sai was the only okinawan tool designed to be a weapon only, the rest were formed from farm tools.

The word sai is also spelled psi due to confusion about the transliteration from Japanese and because of its fortuitous similarity in shape to the Greek letter psi (ψ).

The jitte is a one-pronged variant used predominantly by the okinawan police in the Edo period, when Okinawans were forbidden to carry bladed weapons.

Sai have also been featured in various mainstream fiction and video games. Raphael (Ninja Turtle), Mileena from Mortal Kombat, Gabrielle from Xena: Warrior Princess, and Elektra (comics) are sai-wielders.