It's the life-size Termie suit that Games Workshop has in their HQ (they have a museum-type place called Warhammer World there, IIRC). I remember seeing photos of some guys posing in it in a copy of Inferno! some years ago.
EDIT: What's with that power fist? Looks strange.
It looks strange because all there is, is a shoulder and a hand and no arm in-between.
The shoulder pads are too small as well. I think there are some problems when you scale some WH40K armour designs up to make them "life-size". Some of the artwork of Space Marine Terminators suggests things are a little out of proportion in relation to "normal" limb lengths....but then again, when you're an 8 to 9 foot tall genetically modified uber-human/killing machine I suppose that's what you might expect.
Speaking of 40K - here's
a message from the Inquisition.
