What all does the Echo actually do? [Spoilers]

[Xirean]

I've been going back through some of the previous expansion content and have been wondering what all the Echo actually does. There's multiple people who have it but the abilities it grants are not all consistent.

As far as I can tell the only major consistent ability is hearing Hadelyn's chant and having visions of the past. Other's are able to understand creatures that regular people can't (Kryle). It seems to be what allows the baddies to switch bodies and if you take gameplay as an example then it makes us progressively stronger, though I'm not sure that one counts.

Also is there a distinction between the blessing of light and the Echo? Kryle seems to refer to them as the same thing; yet when we met Midgardsormr and were effectively stripped, the Ascian was able to get into our stronghold while Minfilia was inside.

Also if anybody knows how to spoiler tag text let me know and I'll gladly edit this post. New here :P