Why is she wearing an archer's breast plate? I've never heard of crossbows having to be strung back in the same fashion as a normal bow.
Simple, that's a modern style crossbow with a shoulder stock (old-style crossbows were held under the arm, like a lance). You try resting a stock on a normal breast plate. Not comfortable or remotely accurate. That's why modern Hard Bullet Resistant Vests have what's known as the 'shooter's cut', which is basically modern archer armor. (Seriously, they work pretty well with archery)