Legendary Weapons of China is a martial arts fantasy film taking place during the late Qing Dynasty when Empress Dowager Cixi dispatches her agents to various factions of the Boxer Rebellion in order find supernatural martial artists that are invulnerable to western bullets. When one of the leaders of these groups disbands his forces, assassins from the remaining factions are sent out to kill him.

Twins, separated at birth, end up as a Hong Kong gangster and a New York concert pianist. When the pianist travels to Hong Kong for a concert, the two inevitably get mistaken for each other.

The Yangs are betrayed by a government official conspiring with the Mongols. All of the Yang family males except the 5th and 6th brother are killed. Fu Sheng loses his mind after the death of his family, while the other brother takes refuge in a Buddhist temple.