Certain jobs have skills in ranged weapons, but never use them. Why? because they would rather equip an ammo slot item to increase their melee damage. They can't change the item in their ranged slot as it makes them lose all their tp. I suggest making it so you can equip any ammo with any weapon. That way A thief could equip a Yetshila with a crossbow, and switch to acid bolts when he needs to lower defense.