[whswhs]

If you use the Magic as Powers rules, you could buy the armor as a Strength power, with gadget modifiers, and also with the Magical modifier (-10%).

If you are using standard mana-based magic, you could come up with specifications for an enchanted item that casts a strength-enhancing spell on the wearer; there is such a spell in the Body Control college. There aren't any systematic rules for determining the costs and requisites of enchantment, so you would need to improvise those.