I dunno... it makes no sense to me for the Warden (or Alistair) to throw away their weapon at that critical moment and grab a corpse!sword. I guess I just don't have a very good imagination. (In addition to being slow on the up take.)
Also, don't get me started on Teh Murder Knife... WHERE DO THEY COME FROM???? Some invisible back sheath? Is it a Ferelden thing? And why is Isolde carrying? WHHHHYYYYY????
Edit because spelling.
Same. It makes even less sense if you're playing as a non-Arcane Warrior mage (only when I play Amell Warden) and have pretty much no points into strength. The minimum strength requirement is around 18 and by end-game, my non-Arcane Warrior mages have around 14-15 strength. Logically, they shouldn't be able to pick up the damn thing without dragging it behind them. And honestly, who wouldn't use their own sword, axe, whatever to kill the archdemon?
Come to think of it, since when does a non-2-hander Warden know how to wield a greatsword? I found it completely ridiculous to see my Amell Spirit Healer charge at the archdemon, wielding a greatsword like it weighed nothing and she'd had years of experience with it. And not the funny kind of ridiculous either. I mean, my Arcane Warrior/Blood Mage Surana wielding it was kind of funny considering how small she was, but I could have equipped her with one at any time. You could get through the archdemon's hide with a sword, dagger, axe, greatsword, or battleaxe, so the Warden doesn't have to use that damn greatsword. Especially since they stab down into the damn thing's neck.
Actually, how would an archer/non-Arcane Warrior Warden be able to put enough strength into stabbing the archdemon to go through the spine? I mean, unless they manage to magically get the blade in between two of the vertebrae and sever the spinal cord, they would have to put a ton of strength into the blow to get through the bone. 