Please, Fanriel is a formidable Loremaster of her own right and one of Aenarion's Bloodline plus she can transform with her beast form if she wanted to. What can one angry puppy of Ulric can do to her?
I mean, the average knight in the Empire has prowess 20. Urskoy had prowess 22. This guy commands a bunch of inner circle knights, who at a guess I'd assume have prowess 25 as particularly elite knights, and as someone even higher on the totem pole whom Fanriel describes as the broadest man she'd ever laid eyes on I'd expect him to have prowess in the high twenties, being basically our equal give or take a point or two.
In terms of equipment I'd be inclined to give us a considerable edge. He seems to be wielding mundane axes and a magical suit of armor a long with a giant wolf pelt. So weapon wise we're considerably ahead, and I'd imagine that armor wise we're moderately ahead.
The big question mark is supernatural powers. We're a mage, but our spell line doesn't count many of the sort of buff spells that you'd want for something like a duel. In contrast we know the warrior priests here can cast miracles. He might be able to pull ahead of us in that regard.
So dividing the parameters that seem like they should affect chances in a duel I'd say the situation seems to be:
Prowess score: Even
Equipment: Advantage Fanriel
Supernatural powers: Ambiguous, inclined to give the advantage to the priest.
So yeah, I can see him being basically our equal in a fight, in the sense that his miracles could cancel out our advantage from superior equipment.