The odds really aren't that fair. There are four of you vs. one of her. I mean, she has the guards, but it's not really a one on one dual as they're mostly trash. (Unless, of course, you game the system and bring just the warden. Then, I suppose that Cauthrien has the advantage with her trash mobs.)

Regardless, that she's not even a Bann makes me think that there may be more to Fereldan politics than who can kill who in solo combat. Because she's generally seen as just a knight while Anora is Queen, and Loghain is Regent...and she's generally considered harder to kill than Loghain. (And you never even fight Anora. I wonder if she's just that awesome?)

And the Warden does beat the arch demon, but again with several armies, a full party, etc. I'm fairly sure that if it was arch-demon vs. lone warden that the warden would lose, no matter how awesome he or she is. Then again, probably someone has managed to do this...but it's not really a normal game scenario to deliberately storm Fort Drakon alone, then to refuse to use the army summoner.

I think that it really points to that Fereldan politics are not determined entirely by who kills who in a dual. I mean, they are in the game, but that's mostly game mechanics + either the Landsmeet voted for you and Loghain is just being a dick, or alternately, the Landsmeet voted against you, but got freaked out when you just started slaughtering everyone and figured "what the heck, he's the son of Maric, and we really don't want to have to clean up any more bloodstains..."