Actually, I think we gave him most of an origin in Roger Stern’s and my IRON MAN run. Or at least more of one than he’d had before.

I think we were planning to eventually reveal that he’d been created as a defense against Celestials, but I’m pretty sure that didn’t get into that particular story.

oh hey I actually just read this! It’s Iron Man vol 3 issues 23-25 there’s a whole Ultimo arc. It’s also all part of the origin (I dunno if it was for the first time they revealed this, but it was the first time for ME) of Sapper and Golden-Blade (issue #24, specifically). 

According to issues 24 and 25, he was all murderizing a bunch of poor alien civilizations:

including poor Sapper’s peoples

who TRIED to murderize Ultimo right back

buuut they didn’t succeed too well and ended up crashing on Earth. Where they apparently crashed on top of the poor guy who ends up becoming Golden-Blade.

Meanwhile apparently Ultimo crashes in China

aaand…. yeah, that’s about it! Sapper and Golden-Blade aren’t villains, they’ve just been trying to suck up enough energy to get Sapper’s spaceship up and running again. 

Meanwhile, that hinting at a celestial murder defense origin thing Busiek ^ mentioned I assume is this panel:

\o/! So there you have it, Ultimo’s almost!origin, as far as I’ve seen it.

Not only the origin of Sapper and Goldenblade, but the first time Goldenblade had a name, too…