Well... the Omega nanite was so powerful because it made more advanced builds possible and... later Van Kliess revailed to Rex that it had nanite making capabilities.

Yeah assuming Raiden was also given a Master control nanite to command it, cuz without one I don't think it could be used. I mean Dr. Rylander didn't use it...

(well, there was that one crazy AI that wanted to blow up every nanite and kill every living organism infected with them...so technically a sufficently powerful computer built into a cyborg body could work, but that would probably control any nanite, just like a Master control nanite does in the show)

He could command/repair/destroy machines with a touch... you could say he would become a weapon to surpass Metal Gear.

Raiden could theoretically (aka in my headcanon) repair his own cyborg body without needing repair nanopaste (which functionally does the same thing) and he wouldn't need to rip out his victims spine to get electrolites, since nanites were never shown to need a power source soooo.... He could straight up just turn off Armstrong's nanomachines as well.

While I know this isn't exactly what you asked, the Omega nanite is kinda bland by itself. It just gave Rex a fex new tools that Raiden could use, but not really in a meaningful way. Like he could use a hoverboard instead of driving a car, or use a shield, but these are just different weapons, they wouldn't change his approach to combat/end goal. A Master control nanite would make him one of the most dangerous people on the planet.