Take the Woven Wand to Bethor Iceshard in the Magic Quarter of the Undercity.
Thule once told me that, long ago, he and two colleagues created a magic wand, woven together from the apprentice wands each mage possessed. This wand was a symbol of their friendship, and although Thule came to despise it he could not part with it, nor could he let the others have it. So he stole the wand, and hid it in Fenris Keep.
Here. Take the wand to Bethor Iceshard, one of Thule's friends from years past. I'm sure he will want it.