Sai ( ˈ s aɪ ʃ ə ) is a type of traditional, single-edged, sharpened knife that is used as either an offensive or defensive weapon in many martial arts and historical combative systems. It is described as the “shortest blade you’ll ever have to find room for.” The Sai weapon can vary in length and size but most are about 8" (~20cm) long. The practitioner typically keeps their sai sheathed on their waist or in the scabbard at their back.
The word sai comes from the Chinese sword with different pronunciations in Japanese or Korean (Chinese character 薩). In Japanese it is called セイ ( sei ) and in Korean as 목 ( mok ). During the Zhou Dynasty, the Chinese developed a small sword called “sai”, after the blades of this period appeared with resemblance to those swords of Southeast Asian cultures. It was around this time that the character 薩 ( sai ) first appeared in Chinese texts.
Later, Middle Han, Tang Dynasty, and Song Dynasty texts refer to “sai” as a short sword. During periods when short swords were popular among Chinese generals and warriors, various poetry and martial arts writings refer to it as a sai or yuetse.
