Idea for a completely new Job.

[Enkidoh]

It's a big spoiler, but the 'dragon transformation' thing was explained in Heavensward's storyline

: all native-born Ishgardian elezen, that is, those who claim descent from King Thordan and the Knights Twelve, all carry fragments of dragon essence within them, due to Thordan and the Knights devouring Rattasokr's eyes and infusing themselves with her draconic essence. This 'taint' is therefore passed down through all Ishgardians, who are actually unaware of it.

Heretics become aware of this and after turning their backs on Ishgard's lies, are rewarded with the pledge to the Dravanians by being allowed a sip of dragon blood, which causes the dormant dragon essence within them to awaken.... and results in their transformation as a dragon them self. Apparently this transformation is not reversible either, which does make one wonder how we will able to deal with a certain Azure DRG, but that's another barrel of moogles.

Either way, because the player is canonically not native Ishgardian (narrative wise the player is from another land outside Eorzea)

, your idea just wouldn't work I'm afraid. I think the SMN lvl 3 Limit Break is about the closest you're going to get to this idea I'm sorry to say.