This would take a bit of work, but not nearly as much as you would think as most of the functionality is already there. That is, it could use an Inventory, with some "projectiles" being given a flag that they go into the second list as opposed the first. If items in the inventory can't actually be selected, then it only exists to modify the character's stats. The hard part would be adding in more functionality in how an object can affect it's holder, and some "coding" to give the character an object when they are hit by another projectile.
It could add a whole lot in terms of what you can do. The only real reason why it can't be done (at least in some form) now is that I'd be leery about using up already existing slots, and the possibility that it could be fired off and "gotten rid of" that way.
Sound doable, masters of Myth?
