So Endwalker gave us further revelations on the nature of the Blessing of Light (and a little bit on the Echo), and I am pretty sure I understood everything, but I also want to ask for clarification on a few things.
So, the Blessing of Light is revealed to be an extension/evolution of Venat's own original Magick that protects individuals from aetheric corruption (i.e. tempering), and as Elidibus and Urianger surmise in 5.2, Hydaelyn/(Venat) grants anyone who naturally awakens to the Echo (who isn't an Ascian) the Blessing of Light. And therefore, the Blessing of Light is not Hydaelyn tempering people.
Additionally the Blessing of Light can also empower people further, especially if they have/generated a Crystal of Light (in the WoL's case we have 6 Crystals of Light), but having a Crystal of Light is not a requirement for having the Blessing of Light itself (as per previously mentioned in the 5.2 musings and Krile herself already stated in 3.1 that she has the Blessing of Light).
And presumably even after Hydaelyn/(Venat) has died, her Blessing of Light Magick still remains on the people who have it, it presumably is not a Magick that fades after the casters death. However, also presumably, since Hydaelyn/(Venat) is now dead no one else in the future can receive the Blessing of Light anymore (at least not the Magick Venat created), even if future people are born with/awaken to the Echo.
Also, if I have understood correctly, the Echo itself also well protects people from being tempered by Primals/aetheric corruption, as evidenced by the WoL still having tempering protection/immunity after Midgardsormr temporarily stripped us of the Blessing of Light right before Heavensward, and the fact that people with an artificial Echo (Zenos, Fordola, and Misija), but who don't have a Blessing of Light, are also still protected/immune to tempering.
However, the protection from tempering that the Echo provides isn't as absolute/strong as the tempering protection that the Blessing of Light can provide, as evidenced by the fact that Emet-Selch stated that Zodiark tempered the Convocation after his summoning, despite the fact the Ancients would have also been in possession of the Echo (and presumably would have been even more powerful in its mastery than a sundered soul individual with the Echo can have). So, if we are to believe Zenos' theory in Stormblood in regards to how the Echo works, the Echo only gives protection from tempering/aetheric corruption in the sense that it allows people with the Echo to have a greater "will" than Primals, and therefore "dominate" the Primals instead of being dominated by them, effectively being protected from tempering. But presumably a super powerful Primal like Zodiark (as stated by Emet-Selch) is strong enough to overcome the protection the Echo can provide against tempering/aetheric corruption.
So does my summation of the Echo and Blessing of Light sound about right/is accurate?