I was blind...but now I see...

Sometimes, I find a good way to look for inspiration is to work out what precisely what something isn't, in addition to what it is. Ynnead is the Eldar God of Death and Rebirth. Ynnead is not God of Healing. That's Isha's domain, who still lingers on in Nurgle's company.

Ynnead has power of life and death over the bodies of the Eldar, independent of their condition. We see this in the Altansari, saved from death by the power of Ynnead, but appearing as perfectly preserved corpses. Perhaps in time she will gain power over this, but for now she is weak. A small fish in a pond full of sharks. For now, simple animation will have to suffice. Hence the term 'Revenant Psyker'. What precisely do you think these Eldar should look like?

Slain by the blinding psychic light of a fell Sorceror, Ynnead has the power to restore life to your limbs. However, Ynnead does not have the power to restore sight to your eyes.

For Laeril, wraithsight would have to suffice. The alternative, she supposed, would be unimaginably worse.