Ultima behind everything?

[Lyth]

The E11S fight is 'Mitron Prime' utilizing Ryne's hopes and fears against her, which is why the Fatebreaker is a Thancred/Ran'jit hybrid. Mitron wanted to break her spirit, similar to how being confronted with their darkest fears made manifest broke the spirit of the Amaurotine people during the Final Days. Hence his follow-up line:

'That fragmented souls should triumph over their fears while we succumbed to ours, thereby setting our star upon a course of ruin... That inferior beings such as you should succeed while we failed! It defies all logic!'

It's a bit trickier to reach a conclusion about the E10S fight. From a practical standpoint, the role quests with Cylva are side-content that the player may not have have personally experienced yet. Having you fight the Shadowkeeper in wolf form preserves the mystery, although if you've done the quests you appreciate the reference to Cylva's sword. I'm not sure that Mitron is trying to invoke Gaia's fears here, so much as he is trying to get her to remember her former life as Loghrif.

The true events could have played out either way. Mitron and Loghrif's plan was for Ardbert to strike down the Shadowkeeper and trigger a Flood of Light. Could that happen from a conflict with a regular person? Or would they have to be darkness-aspected first, similar to our clashes with the Lightwardens? It could be a stylistic choice, or it could be that Cylva actually transformed to fight Ardbert so that she could trigger a light-aspected flood.

With regards to the thread topic, I wonder if the 'eye-symbol' is less of a reference to Ultima than it is to Athena, given the Greek symbolism involving owls ('bright-eyed'). You also see an eye in the background in the P8S fight, which is notable during the phase transition. I think we can safely expect more Lucavi references at some point in the future, but I hope that this is just a once off connection.

[Iscah]

Having you fight the Shadowkeeper in wolf form preserves the mystery, although if you've done the quests you appreciate the reference to Cylva's sword.

Also the shape of the "true form" shadow is an elf rather than a wolf.