Now it's been long known that the Upper Blackrock Spire (or UBRS for short) key quest has been bugged for quite some time now. But what hasn't been divulged was the fact that the quest isn't all entirely unachievable, unlike some really buggy key quests out there.

Interestingly, the part of the quest chain called the "Seal of Ascension" was particularly difficult, since after giving the Unadorned Seal and the gems, you couldn't finish the quest at all. So if you have activated the quest some time ago, you might want to drop it and then reacquire the three gemstones and two Unadorned Seals of Ascension to Vaelan.

Take note: you must bring TWO Unadorned Seals of Ascension together with the three stones. Once this has been accomplished, you'll be able to re-accept the quest and be achieve the quest's objectives. Cobain, a Level 70 Human Paladin, discovered this solution through trial and error. He said:

What I did was [I simply] abandoned the quest and continued to kill trash mobs until I found another Unadorned Seal of Ascension. I then went back to Vaelan and I was able to re-accept the quest, [break] the dragon's will and [turn] it in without [failure]. It appears that you are required to have [an] Unadorned Seal of Ascension in your bag to speak with Vaelan even after you have collected the three stones.