I won! Somehow, impossibly, he became less lethal while wielding a lethal weapon. I cheated by console command spawning a chitin dagger into his inventory so he would use that in our fight. I got so sick of being staggered and having my fatigue drained to the point where I could not connect even one swing unless I was very, very lucky, but the guy is level 5 so nothing I have at level 1 can possibly one-shot him, and he ends up actually winning. Granted I've just started a brand new level 1 character who is not focused heavily on any melee weapon skill, but Foryn Gilnith is somehow beating me senseless every single time I load and try to confront him about the murdered tax collector in Seyda Neen. Somehow losing all of my fatigue at low levels is incredibly more devastating than facing an opponent who 'only' does damage to my health, but leaves my precious fatigue untouched so I can actually connect my swings.