Well...not necessarily. Usually I have either my Warden or Morrigan defeat him. I suppose the vouching part, but really?

If the criteria for running the country is being the #1 best fighter, we ought to be celebrating Cauthrien as queen. (Unless, of course, your Warden does the weird thing that one guy did and kills her singlehandedly with his arcane mage or whatever.)

...alternately, this theory would also support the arch-demon's claim to be King of Ferelden.