User blog comment:Greenberet69/The Balrog vs The Archdemon/@comment-4552610-20111102174739/@comment-422690-20111102175333

No, the Archdemon was defeated by a massive co-ordination of people. First, Riordan had to weaken it, then a bunch of Denerim's soldiers weakened it more, and then the Warden and his party, assisted by the armies they'd collected, came in and finished the job. The Archdemon required the cooperation of all the forces in Fereldan to beat, the Balrog required one man.

Also note that the first Blight, lead by the first Archdemon, went on for 192 years before someone managed to kill the Archdemon at the cost of all his own soldiers and his life.