There's plenty of reason to take it over Channelling. For example, maybe you don't have much Lore, Discipline, and Conviction.
I mean, Breath Weapon is pretty weak. But there are many situations where Channelling is even worse.
While I like the idea of upgrading Breath Weapon, I think the upgraded version should remain generic. Claws and Breath Weapon are extremely broadly useful, so they end up on all kinds of characters.
And if the upgraded version is as niche as this one, then it's not useful for the vast majority of those characters.
I took a shot at Claws and Breath Weapon with Natural Weaponry, which is honestly still pretty conservative power-wise. I've considered making it weapon 3 base, because that's what good mundane weapons offer. I don't think it would break anything.