The Korean war fan (mubuchae; Hangul: 무부채) was a Korean martial arts weapon that originated in the Joseon Dynasty of Korea. Swords and similar weapons were banned from most people during this time which created a need for weapons that could be held in plain sight without arousing suspicion. They became most popular among the chungin (middle class) and yangban (upper class).
Craftsmen discovered a way of taking the "pak dahl" wood, an extremely resilient birch tree that thrived in the ice storms and harsh seasons of Korea's mountainous peninsula, and tempering it to a hardness that could resist the edged weapons typical of the era.
Following traditions of traditional weaponry, Korean war fans were often unique to their wielder and bore many possible combinations.
Some wove flexible metal ribbons along the outer most edge for cutting power or preferred feathers that hid finger-sized razor blades which would rake upon striking. Others held variations of poisons or were used to conceal other weapons such as throwing blades which could be released in a spread upon snapping the fan open, a technique a few Kook Sool Won (Guksulwon) artists are said to practice.
Poison fans often hid deadly or stunning concoctions in bladders or channels which would open upon spreading the fan, allowing the user to gently direct a gust of irritants and toxins at their opponent over short distances.
Folklore and hearsay also suggests occasional traveling merchants trading with China possessed fans with small compartments in the vanes of the fan which held small explosive pellets that upon striking a surface would create a bright and dazzling flash of light, similar in concept to modern Chinese novelty fireworks.