I do like the Aleph models. They are unlike anything else in 40K. My thought had been to use Tau Battlesuits, but to have some non-40K is probably best.
I like the idea of joints and seams glowing as well. To have just glowing eyes feels too Necron to me. They should not be seen as soulless either. Quiet the opposite, all they are is souls.
That is a good glow look jonileth. It looks pure and benevolent, evoking curiosity. Is that the shape you were thinking of for a Gnosis outside a proxy body. It looks good and gives me an idea.
The image and description originally presented remind me of Will-o'-Wisps from D&D. Like those, a Gnosis in its "true" form could evoke curiosity and confusion in those who see it. We could even model them with modified/converted Tyranid Spore Mines or something. I suggest this because I would imagine a Gnosis in a Proxy to not be a cheap unit to field. Their rightous glow would probably give them the Fear rule and those in vehicles would have a Hule Point boost perhaps. But those not in a Proxy could be joined to units. As they are incorporeal, they can't be hurt but would benefitt the unit they join. Their unit would get a Leadership bonus for their inspiring presence and enemies shooting the unit could get -1 BS if the Gnosis is the closest model, like it's confusing them. Maybe Fearless units are immune to that.
I know it's too early to talk rules. But I wanted to explain my reasoning for wanting to model a Gnosis in "true" form. And of course, if the unit it joins is destroyed, it is removed from play. Perhaps further benefitts can be gained with multiple Gnosis in one unit.
"Fetch me another plaything. This one seems to have broken." -Urien Rakarth
Space Marine- "This planet is ours, witch."
Eldar- "No ... This planet is theirs ..."