As I understand it, variable descriptor just lets you change what type of effect. Perfect for weaponry, since variable can be slashing, piercing, bludgeoning, etc.
It would probably be easier to just purchase blast with variable descriptor (energy, ballistic, piercing, slashing) to account for energy weapons, guns, or thrown weapons that he may use. Then, AP a strike off of it with variable descriptor (energy, slashing, bludgeoning, piercing) to account for melee weapons. The shield could be similar, and the armor would just be the base device that everything else is built into, I guess.
Still interested in the idea of copying other technology, though. Maybe a mimic, limited to technological devices? That could keep the variable power out of it (kind of), and he could power stunt past configurations off of the main power with extra effort.