If you truly bear Quel'Delar, <name>, I might be able to admit you to the Sunwell. If you know the blade's history, you recall that it was borne by Thalorien Dawnseeker in defense of the Sunwell against the Scourge. He fell in what is now the Dead Scar, buying time for his men to make their own preparations. You will find his remains near the southern end of the Dead Scar on this isle. Visit them, and if his spirit gives you its blessing, I will allow you to enter the Sunwell.
I confess that I did not expect Thalorien's spirit to recognize you as the heir to Quel'Delar, but I defer to his judgment. You may enter the Sunwell, but I remind you that you are a guest in our most sacred of precincts, and you should act accordingly.