I was just thinking that a few (or several) more arrow/bolt types could add some interesting combinations to the game --well, combinations with the bows and crossbows, that is. If you like ranged combat, odds are you already have a favorite or two, or maybe even a whole arsenal.
Now think about combining that favorite bow/crossbow with cursespewing, destruction, keen, paralyzing, smiting, or any other awesome prefix or suffix ammo. A little extra edge, but it's a consumable, takes up a unique spot in inventory, and.. well.. encourages the purchase of better quivers.
Considering that I still don't even have a maxed-out stack of Holy arrows as a Ranger 20, I don't see this as too unbalancing. Plus you'd be the ones to determine how often they drop anyway. So, just asking that you consider more of the prefixes and suffixes already attached to melee weapons.
And maybe a bludgeoning arrow, too. But not vorpal. I think slaying has that one covered.