[Ulzgoroth]

This might be excessively reductionist, but it might not too:

It's gear. And it's not realistic gear, so calibrating it to realism is outright impossible. So what you really need is simply to give it the stats you want it to have. The nominally-realistic armor in UT doesn't go into any detail on how it works and how it's made!

Now to undermine that a little, it probably should cost more than and weigh at least as much as non-powered armor of the same DR.