Are you sure Duncan was the bad guy? This sounds like an episode of "Highlander" starring Adrian Paul as Duncan MacLeod, an immortal who regenerates from injuries.
"Mountain Men" (episode)
When Tessa's ramble in the great outdoors leads to her kidnapping by a group of lawless mountain men, Duncan must find and rescue her before a forced "wedding".
From IMDb review:
Marc Singer adds some acting skills to this better than average episode in this series. Playing a crazed mountain man, who also turns out to be yet another immortal, he kidnaps Tessa while she is exploring the great outdoors. Obessesed with her becoming his wife, he takes her, his adopted son and another mountain loony into the deep woods. Cue Duncan MacLeod to become a Rambo-like Hawkeye Indian tracker type and trail the baddies to a final outcome.
While photographing old petroglyphs in the mountains, Tessa is abducted by mountain men led by Immortal Caleb Cole (Marc Singer), who wants to marry her. ****MacLeod pursues them but must throw himself into a crevasse to escape Cole's henchmen.**** They bring MacLeod's sword back to their camp and Cole realizes MacLeod is Immortal when he sees it. Tessa instigates infighting among the kidnappers, buying MacLeod time to find her. MacLeod then fights and beheads Cole.