The Blade Spares None (1971)

Ho Li-Chun, a pretty but ruthless swordswoman, and three challengers are participating in an open tournament at Prince Kuei's Palace. A knight, Chen Jo-Yu, is defeated in the tournament. He flees and later returns with knight Tang Ching-Yun who wields a strange sword. They get trapped but Ho deliberately sets both free after seeing Tang's weapon which she recognizes as the same weapon once used by Sun Tien-Chen, a foe of the Ho family. She decides to investigate. She finds out Prince Kuei actually is Sun, who killed the real prince years ago and assumed his identity. Ho joins forces with Chen and Tang. The trio slays Sun in a desperate confrontation at the palace.