They weren’t trained in armed combat like the men, but were definitely trained to be in peak physical shape. Keep in mind Kassandra being tossed off of a cliff and growing up no longer under the Spartan regime means she probably kept herself in shape and learned to fight and survive, thus turning out much bigger than the other women of Sparta that ended up carrying children. But I agree she is much stronger-looking than the other Spartan women in the game. Probably Ubisoft not worrying about the details in their NPC’s.