Fierce (A.K.A) Fighting Mad (1978, VHS):
 
An American Vietnam soldier (Leon Issac Kennedy) on his way home is left for dead and is saved by a pair of Japanese stragglers from WWII, who train him in the way of the samurai. Jane Kennedy plays the sexy wife that is used by the scumbags as a helpless pawn, but this does not sway the warrior from exacting his revenge.