"The Keening" is one of the weapons you need to kill Dagoth Ur. But you can only handle the blade with a certain bracer called Wraithguard. When you are Nerevarine and Hotator, you must talk with lord Vivec. He will Give you Wraithguard and all the detail you need to defeat Dagoth Ur.

Quote:

I was wandering about Red Mountain going into temples and plundering what i could find. Then I found a short blade on a on a fansy looking Pedistal with smoke comin from it. I took the blade. But when ever I weild it i die instantly. Will i ever be able to use it?

Yes, but you have to get wraithguard, which is the only gauntlet, which will protect you.(See: Is there a way to get cool?)