User blog comment:Traditionalfire/Why are all Ninjas women? (In games)/@comment-5362182-20120913180924/@comment-24174486-20120916141544

One can assume that Jacob and Miranda's outfits are made of space-kelvar. Samara's outfit does seem to be some sort of armour, albeit thin and revealing. Jack would rely mostly on her barriers, although she is quite squishy. (Garrus also has a reputation for being a Glass Cannon, so his armour might not be very effective anyway. XD)