This quest requires completion of The Hand of Glory (Quest) and starts by reading Greigor's journal.
After acquiring The Hand of Glory, you feel the curse has been put on you.
If you wish to remove the curse, there are 2 options for breaking The Hand of Glory's curse.
Giving the hand to Eriana
The first option is pass the Hand of Glory on to Eriana.
Go to the Explorer's Society Guild House and talk to Eriana about the Hand of Glory's curse.
She will dismiss the Hand of Glory's curse as folk tale, but you tell her that The Hand of Glory's power may drain her.
When 2 dialogue options appear, choose the first dialogue option twice to give her the Hand.
If not already completed, Digging Up Explorers must be done.
Another option is to slay Ahtar.
Slaying him also removes the Hand of Glory's curse.
If you want to avoid incurring a bounty upon slaying Ahtar, you may complete his quest to make him a follower, then lead him out of the city.
Also if you still wish to slay Ahtar inside Solitude, just be mindful of possible witnesses.
Since Ahtar isn't set as essential, he can be killed before starting this quest, thus making the Slay Ahtar option unavailble.
Doing this quest removes the power from The Hand of Glory, making it only replica displayed at Hall of Secrets.
If you wish to keep the Hand of Glory's power, do not do this quest until you are ready to break the curse.