"Primarch-Progenitor, to your glory and the glory of Him on Earth!" Normally I don't care much for the Fists, but this made me instantly think of the Iron Cage. Can't tell if that is what you were going for, for this is supremely awesome.
This is some spectacular piece of art. The details are well placed, drawing and keeping the viewers eyes to the helmet. I have to admit though there is one thing that looks (in my eyes at least) kind of odd. At the bottom of the picture, the foreground looks sort of "cut out", it does not connect to the background very well. Hope you dont mind.