I'd like to forward a request to approximate both weapons for ranged combat, because the sling seemed to have been a weapon with equal deadliness in ancient times.
I guess the ancient bows were not that sophisticated as models from more recent periods.
The Balearic slingers might come to mind, who had quite a reputation and (out)matched the common archers and javelin-throwers. Alexander the Great used light infantry with slings, I think I can recall Roman auxilliaries using slings, too.
Though slings seemed to be widely used in RL, the current disadvantagous properties of the sling do not allow it to become a useful weapon in AE.

Also javelins could be implemented as a third kind of ranged weapon. The Pilum, the roman version of a javelin was mentioned at the board before.