Keira Knightley as Guinevere ready for battle. I think that the Picts could have gone to battle in very light armour such as these, but in the case of the women, the breast protectors would've wanted to protect all their breasts, not to show them off. That's not the aim of a breast protector! Apart from that, it's realistic for a very light warrior.
Inspiration for #QueenMorgan le Fay in #KASIWC/King Arthur's Sister in Washington's Court by Kim Iverson Headlee -- though her hair needs to be auburn. (Call it "red" and she will throw you in her dungeon!)