Quote Originally Posted by Eloah View Post
Why would she need the Echo to be a shard buddy
Because Minfilia did have the Echo, just like the unknown Ancient her soul originally belonged to. All other explicit or implicit pairs—the WoL and Ardbert, Unukalhai and Nyelbert, and all of the sundered Ascians, all of them possess the Echo as well. But Ryne, apparently, does not.

Plus while nothing is stated outright, we know Ryne has something, but no name is given, whether it's the Echo or the Blessing of Light is unknown.
This is incorrect. Ryne is explicitly stated to have the Blessing of Light shortly after her first onscreen appearance. She also comments on having it at several points in the story, with the latest being in 5.3, where she remarks that the (Blank) of Light shades summoned to attack the Scions bear the same blessing as both you and her. Notably, that last one is after it's made clear that the Echo is not a gift from Hydaelyn, but rather an intrinsic part of a soul's being.

As we have encountered others without the Echo who have maintained their "sanity" upon becoming a Primal.
I would not describe "screaming in agony mere seconds after summoning Shiva" as "maintaining her sanity". Plus, Gaia rather explicitly points out that Ryne is not the one in control during the fight. Possessing the Echo is an explicit requirement for controlling a primal in this fashion. It's the very reason both Zenos and Misija sought to copy the Echo from others via the Resonance Chambers.

Another thing we learn later is that the Echo is present within everyone, it just needs to be unlocked.
This is just straight up wrong. What we learn is that the Echo is not a gift from Hydaelyn. It's still exceedingly rare, and very few present for the star showers Elidibus created awoke to it.