This is where experimental archaeology could help. If they had access to some guys well trained in contemporary fighting techniques (assuming we know what they were or could approximate them), you could have them fight various scenarios to see which would be more likely to have caused the wounds.
But "more likely" is about the best you could get.
BTW, one of the more interesting observations from medieval cemeteries is the rate of homicide. I read a long time ago that Merovingian era cemeteries in France showed from peri-mortem bone cuts that the leading cause of death for males 15-30 was homicide.
Wow... interesting. I suspect we can scarcely imagine the reality of life back then.