The night elves craft living bows from the trees of their ancient forests. After the war, some of these bows ended up in Forsaken hands, where they underwent a radical change. The unholy energy that animated the Forsaken interacted strangely with the bows, and the living wood withered, dried and died. Now some Forsaken craft these bows deliberately.
These bows appear as ash-gray curves of warped and twisted wood.