Dragon Age Origins, rase weapon Tier?

First I know to raise some weapon Teirs you need to sell them to certain merchants. During my last playthrough I left my Duncan's Sword (red iron) in the chest at Warden's Keep and when I picked it up after completing two quests (A Paragon of her Kind and The Broken Circle) it was raised to Dragonbone. Which merchants do I sell the weapons and armor to to raise the Teirs, and would selling the Chasind Flatblade raise it's Teir?