https://www.youtube.com/watch?v=OzV1GlDDlv8
If you skip to 1:20-1:21 in the gameplay trailer, we'll see what appears to be an odd Power Fist the Sole Survivor has equipped in the scene. By the looks of it, Bethesda has made some new designs on it, putting what appears to be a pad on the front of the weapon instead of on top, most likely where the kinetic energy is stored, possible a piston with a plate inside. The hand isn't protected anymore by any type of slip-on glove material and metal padding, but rather out in the open, the only protection being on the top of the Unarmed weapon, this may be either a new redesign of the Power Fist, an early model of the Power Fist series, Or even a crafted jury-rigged power fist the Sole Survivor made by himself/herself.
On a side note with unarmed, It looks like we still won't be able to dual wield weapons it seems, Which I can understand Guns, Energy Weapons, and even Melee....but Unarmed? The one skill that would actually perform better with two Power Fists instead of one? It just seems rather odd you can't dual-wield Power Fists/claw weapons in FNV/FO3 when nothing would hold you back or hinder your progress if you did so.