'Powered' means only that is has a power source because if it didn't it would be too heavy for a normal person to use. It doesn't necessarily imply a lot of strength. Sure, a small boost due to the reinforced exoskeleton, but it's not like if you put me in one I could suddenly bench 400 pounds. I don't have the strength or stamina necessary to lift something like that normally, and when you factor in that I have to use what strength I do have to move about in this clunky-ass suit - which is probably tiring as well, and IIRC sometimes when it pops up in sci-fi the operator needs special training to use it, which we won't have, being rag-tag rebels and all -any bonuses would be marginal at best. The biggest thing it has going for it is that it can eat a lot of punishment, but it's only for front-line fighting; it's too bulky to be maneuverable and being made mostly of metal it would be loud as hell, which isn't that desirable at the moment given that our operation is mostly hit-and-run sneak attacks and ambushes.
Later on, when the rebellion's big enough that we are on the front lines, power armor would be very desirable. Strength and mobility wouldn't be as necessary on a flat field with no cover, but what amounts to a walking tank certainly would be. I dunno what Draignean has planned for it, I guess we'll have to wait and see. Anyway, even if it's not that good at first, with your crafting skills you could probably improve it. ^^
(As for the Mjolnir armor MC wears, I believe he's a genetically engineered superhuman cyborg in the first place...)