The Savior Advanced Robotic Mobile Suits (or A.R.M.S.) were discovered in a sealed military bunker buried nearly a mile below the City of Iron, unearthed by the dwarves scraping every shred of ore from the endless tunnels and caverns. They seem to have been created by a previous civilization in a time of great conflict, designed to carry elite warriors into battle and protect them from harm while allowing them to carry weapons far beyond the capability of mere humans.
Even Hammerstorm knows there is one thing stronger than the hammer -- the forge. By wrapping himself in the mysterious metallic armor found beneath the City of Iron, he constructs a new, impervious version of the famed, stoic warrior. And the suit lets him carry a bigger hammer, so forget the other stuff.