Bows can roll with +skill bonuses as well, and these will also always get Smart Loot'ed to Demon Hunter skills.
The Smart Drop system ensures that this weapon will always roll with dexterity as the mainstat, regardless of which class finds it. This item can only be equipped by the Demon Hunter, and will rarely drop for any other class. The Raven's Wing is a legendary bow that can be found in Diablo 3 and Reaper of Souls.
