Paladin lore/source of power

[ItMe]

Is it the aether from within or rather divine/faith

You're thinking of a more traditional paladin. In FF14 they're just the bodyguards for Ul'dah's royal family.
Any flavor about "holy" things in their class is just surface fluff inherited from western ideas. Even in other Final Fantasy games Paladins and White Mages don't normally draw their power from the divine / faith like, say, a D&D Paladin does.