I think it is pretty efficient as it is, even without attaching it to an IoP.
If you want to change it's skill to Discipline, I would ask, why you are doing it. Do you have a spellcaster character, that is specialised in combat magic, and you want that power to reflect that? In that case, the ring should probably also be a focus item, to reflect that, and discipline is fair game. If you just want to get a powerup, I would ask why does it have to be a breath weapon ring?
But all that aside:
You can link breath weapon to almost any item and change the appropriate skill accordingly. A ranged weapon of some sort would make the most sense, of course. A magic bow that automatically has an arrow made of fire, once you pull it back. Or a gun, if you want it more modern. Or even a slingshot, if you want. Other things might include a worn glass eye (where discipline or maybe even alertness would be more suited to shoot), a fossilized insect (using survival to attack via a swarm of bees) or an enchanted boxing glove (using fists at range). And of course much more that I can not think of right now.