Are shards different?

[Lurina]

I think (big emphasis on the think lol) that post Rejoining Zodiark would the one to set things back to what they used to be. Those still alive on the Source would be sacrificed as per Emet stated plan, and the now freed Ancients would be granted new life and I assume new bodies. Those who joined the Ascians beforehand, as he clearly tried to get us to do, would also get the same I’d think.

I suppose that's possible, yeah.

The other way you could hodgepodge this all together would be if there was a kinda 'tipping point' where once both the body and soul were fully Rejoined, they would go "Oh wait! I remember what I'm supposed to be!" and snap all the way back to Ancient-hood all at once, like finishing assembling a broken machine. So just having an Unsundered soul in the Sundered world wouldn't be enough.

But both of these sort of feel like doing the story's work for it to me.

(Another manner I guess you could interpret the situation would be that people from the Source are closer to Ancients than they initially appear. Setting aside Ran'jit, who seems to get his supernatural powers from the relationship with his weird dragon spirit thing, magic does seem less prominent in the society of the First versus in Eorzea. You don't really encounter many spellcasters, and the Ronkans, their version of the Allagans, have far more subdued, simplistic magitech. There's no evidence of whole societies of wizards like what emerged during the War of the Magi either.

We know from a couple bits of casual dialogue that being a magic user in this setting can allow you to increase your lifespan by a lot; Ququruka Tataruka is over a century old and still looks like a young Lalafell. Maybe being aetherically dense doesn't lead directly to quantifiable gains in physical strength and vitality for everyone, but instead specifically increases the amount of people with an innate ability to use magic, and makes it easier for those who do. So anybody could learn to do it regardless of their aetheric density, but they'd have to rely more and more on things from their environment, like how non-Ancients have to use reagents to conjure things instead of doing it from pure aether. Individuals can rise high, but civilizations on a broader scale are constrained.

So the Ancients wouldn't be special or stronger by virtue of their biology, but rather because their aetheric density was so high that the rate of what people in Eorzea would call gifted mages, and what in the First would be a once-in-a-generation prodigy, would be basically 100%, with that fact permeating their culture. So kids would learn how to purge their bodies of illness and aging in school, while in Eorzea those techniques are constrained to the most reclusive masters.

Again, though, pure fanwank on my part.)