Echo and Blessing of light, post endwalker retcon

[Denishia]

I don't see a contradiction. They're akin to Galvanize and Catalyze. Echo being Galvanize, easily applied, a shield that can protect against so much corruption. Blessing of Light is Catalyze, and is a much stronger shield than Galvanize. They can stack, so the Blessing of Light being protection against aetherial corruption is not changing that the echo does it too. If anything, it means somebody with the Blessing of Light would be able to essentially take control of a primal like Bahamut or Alexander without their will being taken over, while somebody with just the echo would be likely to be taken over by the elder primal.

I got the same vibe as well. Tempering, as the 5.4-5 patches clarifying, is the overloading of aspected aether, and it's harder to be overwhelmed if the competing aetherial amounts aren't extreme and, through Timat, implied to have a second element in a 'debuff' pull of worship. Worshiping a primal is thus placing oneself in that relationship where the mind-control danger of Tempering is but a natural exaggeration of the summoner/worshipper's own zealotry. The Ascians added a hook to primal summoning to add in that brainwashing/mind-control element - or at least made this drawback stronger and gave the 'control any summoners and create worshippers to sustain and grown' as part of the core programming of all primals even if the summoners weren't intending that as part of their mental image of their primal god's motivations. Tiamat summoning Bahamut had less a pull on those two 'debuffs' that create the Tempering we're familiar with. But Primal Tempering is a two-fold problem in most modern cases. We learn that the Blessing of Light is focused mostly as an aether shield (which makes sense considering its use as the shield that saved us from the point-blank Ultima Spell in the Praetorium) and that the WoL innately has a dense and vast personal aether that grants us a strong constitution against primals and gives us the pool to learn the various jobs, teleport around the map, and prove the aether powerups to our friends in various solo duties. Now we now the Echo also protects against primals (though while canon hasn't thought us otherwise, it has not 100% ruled out the chance that a primal might have enough aether to overwhelm the Echo buff) for others like Arenvald, Ysyale, Fordola, etc... I wouldn't be surprised if lore later clears up that the Echo, as part of the more mental/understanding the souls of others, is a shield that is focused on combating the mind control debuff and the Blessing is that second stronger shield against the overwhelming weight of foreign aether (which is the 'Tempering' danger of Zodiark, the tug that the Lopporits mentioned) that our regular giant aetherpool point bar can't soak.

[Theozilla]

I got the same vibe as well. Tempering, as the 5.4-5 patches clarifying, is the overloading of aspected aether, and it's harder to be overwhelmed if the competing aetherial amounts aren't extreme and, through Timat, implied to have a second element in a 'debuff' pull of worship. Worshiping a primal is thus placing oneself in that relationship where the mind-control danger of Tempering is but a natural exaggeration of the summoner/worshipper's own zealotry. The Ascians added a hook to primal summoning to add in that brainwashing/mind-control element - or at least made this drawback stronger and gave the 'control any summoners and create worshippers to sustain and grown' as part of the core programming of all primals even if the summoners weren't intending that as part of their mental image of their primal god's motivations. Tiamat summoning Bahamut had less a pull on those two 'debuffs' that create the Tempering we're familiar with. But Primal Tempering is a two-fold problem in most modern cases. We learn that the Blessing of Light is focused mostly as an aether shield (which makes sense considering its use as the shield that saved us from the point-blank Ultima Spell in the Praetorium) and that the WoL innately has a dense and vast personal aether that grants us a strong constitution against primals and gives us the pool to learn the various jobs, teleport around the map, and prove the aether powerups to our friends in various solo duties. Now we now the Echo also protects against primals (though while canon hasn't thought us otherwise, it has not 100% ruled out the chance that a primal might have enough aether to overwhelm the Echo buff) for others like Arenvald, Ysyale, Fordola, etc... I wouldn't be surprised if lore later clears up that the Echo, as part of the more mental/understanding the souls of others, is a shield that is focused on combating the mind control debuff and the Blessing is that second stronger shield against the overwhelming weight of foreign aether (which is the 'Tempering' danger of Zodiark, the tug that the Lopporits mentioned) that our regular giant aetherpool point bar can't soak.

Ysayle and Arenvald also had the Blessing of Light, remember Elidibus and Urianger discussed in 5.2, that whenever the Echo is naturally awoken in individuals (who aren’t Ascians), Hydaelyn automatically granted them the Blessing Light. Furthermore, Ysayle also had her own Crystal of Light (like Ardbert and co.) powering up her Blessing even further (and could also use it as an energy source for becoming Shiva).

My big question that's been in my head is 'what now?'

Hydaelyn is no more - will the Blessing of Light and the Echo eventually fade away? Or are we more than just her #1 Tempered-but-not-exactly super-agent; given that we're Azem reborn - technically we're an Ascian of sorts - will it just evolve to not need our Primal in the wings fueling it.

The WoL isn’t and never has been tempered though. And remember the Blessing of Light (or at least what it’s prototype was) existed even before Venat became Hydaelyn, it’s not based on a Primal power but Venat’s own original magick.

Presumably the Blessing of Light doesn’t cease to exist just because Hydaelyn died (as it appears to be a magick that once cast isn’t dependent on its caster to maintain its existence/function, for example like the Tonberry curse/disease from the Scholar quests).
However, since Hydaelyn is dead, presumably no more new Blessings of Light will be granted to individuals in the future, so in that sense it will “fade” once the last person with the Blessing of Light has passed away.

Also remember that the Echo isn’t created by Hydaelyn, it’s a inherent part of souls reawakening to their Ancient souls’ power. So people probably can and will still be born and/naturally awaken to it (though they might be less frequent since Hydaelyn won’t be creating visions of comets/meteors when she needs a bunch of people awakened to the Echo).