Katniss will, in all likelihood, be able to "borrow" a bow from one of the dead, if she so wishes. There are certainly enough littering the battlefield, including a fair amount around Galadriel. If she's in trouble, it's only as much as anyone else on the field; her sword, face, and hair are stained with blood. At Katniss's approach, she will turn and shout to her.

"This is no place for a child! Flee, if you can!"