you will eventually get metal (iron) that you can give her when you use her skill to "reforge" the weapon if it is in your inventory and not equipped.
I have iron, I have the Rusty Short Sword, I can 'reforge' weapons, but I still can't do anything with the Rusty Sword. It just asks me to give her Steel or Damascus Iron and I checked the Damascus Iron and no Rusty Short Sword.
