Crippled Avengers (1978)

A rich warlord who became evil and bitter because of his wife's murder and the amputation of his son's hands now bullies a town through terror and force. The warlord and his now-disabled son find pleasure and satisfaction in life by disabling anyone who gets in their way. Four of these victims--a hawker who has been blinded, a blacksmith who has been made deaf and mute, a drifter who has had both of his legs amputated, and the pupil of an elderly martial-arts teacher who has been made insane, all four of them because of the warlord and his son--band together and learn kung fu with the teacher's help in order to have their revenge on their enemies and use their disabilities to the best of their advantage against them in battle. The four men are tested time and time again and all four of them demonstrate their strengths and abilities to the utmost.