The deathclaw gauntlet is the hand of a deathclaw strapped to the user's arm. It ignores enemy armor, as did the version in Fallout 3, and looks visually identical. The weapon was previously cut content, but was then added in the Lonesome Road add-on in the form of the Fist of Rawr.
The unique deathclaw gauntlet can be obtained from Rawr, a variant of deathclaw in a dark cave, just past the Boxwood hotel roof. He will drop a unique deathclaw hand that is larger than the others, and therefore, you can make a gauntlet out of it.