I can picture a few dastardly uses for this armor.
Desperate warriors needing to hold a pass long enough for reinforcements to arrive. How to decide who will wear the armor?
The villain pays off a few unwitting villagers to hold off the PCs for a time, neglecting to describe the full purpose of the armor being "gifted" to them.
I love subs that get my mind working on all the possible applications.
I'm always impressed by those who can be so efficient in their use of words. This is something I try for but tend to fall short of. I may just add my own attempts to this list. My all-time favorite is Hemingway's six-word short story ("For sale: baby shoes, never worn.")
Took me awhile to get through, of course, but this is a truly impressive piece. Kudos to all of the work that went into it. The flavor is unmistakable, the setting well defined, the plot woven throughout. The setting itself is usable far beyond the included adventure. I especially love the idea of the lush caves hidden beneath the dry desert. If I ever run a desert campaign, I will have to use this.
I don't see how I could give this anything but a 5/5.
While I would certainly run this as an immortal son of a goddess, I would also make full use of the red herrings provided to thoroughly confuse my players. Especially if they had a stake in whatever possible changes might be coming and need to discover if Jaith is merely a messenger or an active participant.