It was my dad who remembered this film about a one-armed swordsman back in the 70s. He has never seen it since, but recently it was released on DVD. Now one of the most hard-to-find films is easier to buy :)
The One-Armed Swordsmen starts with the evil villian Brother Dragon attacking a swordsman, cutting off one of his arms. Before Dragon can finish him, his arm is kindly removed by another swordsman and runs away, never to be seen... however, when a little girl's teacher is killed by a one-armed swordsman right in front of her eyes, suspicion is raised among all one-armed swordsmen that pass by the village.
If you love these kind of films, it's worth a look. The story is clever with some nice twists, and though you can guess who the murderer is near the end of the film the way in which he operated is still mysterious. It also has plenty of fight scenes which are fun to watch (as always).