Keening (Skyrim)

Keening is a legendary Short Blade crafted by the Dwemer Tonal Architect Lord Kragenac. Together with Sunder and Wraithguard, these tools are necessary to handle the Heart of Lorkhan. All three artifacts came into the possession of the Almsivi following the Battle of Red Mountain. Keening, along with Sunder, was subsequently lost during an annual pilgrimage to the Heart, sometime in the Third Era.

Carried by Dagoth Odros in the citadel of Odrosal, south-east of Dagoth Ur's Citadel in the center of the island.

This artifact is obtained during the end of the Main Quest and is required in order to finish it. You can get the weapon at any time, but you can't equip it for very long, since it has the 'mortal wound' ability. Once you have Wraithguard (and have it equipped), this will no longer happen.