So the Stryxis employ aetheric blades of 'ghostlight' that the Eldar deem anathema. If such a blade is brought into contact with psychic or warp stuff, it goes inert for days.

To me it seems the Stryxis have some kind of Necron weapons. Necrons are anti-warp, can't stand psychic powers, and the C'tan fought long wars with the Eldar gods in aeons past.

Doncha think?

Ya know, at first I was going to complain about people trying to tie something else to the Necrons (people were musing about the Crystal Heart trophy in Fortress Erioch, the heart of Lady Malys, and the Warp Gate, and half a dozen other things, not too long ago)...

But taking a second longer to think about the Stryxis, and how they're scavengers, it starts to make a bit more sense. Though they do have technology of their own, that hardly stops them from grabbing everything they find.

So in this case, go Necrons (and Xenos who steal their lewt).

In Edge of the Abyss, it's specifically stated that no one knows why aether blades shortcircuit when contacting psychic energy. Attention is drawn to this fact.

Not for nothing, I am assuming

I'd never associated it with Necrons, since there are plenty of un-named races in the 40k universe, plenty of which dislike psychic powers and the warp.

To me, this does just sound like someone trying to tie the Necrons into everything.

Êven if the weapons use some necron-like tech, it doesn't mean they're directly related. They could be an independent application of the same physical principles. Or something the stryxis extrapolated from some bits of broken necron tech ratehr than a full-fledged port.

I checked the description again, and I must politely disagree entirely with the Necron theory.

First, lets look at the nature of Aether weapons' damage. They pass through all (unwarded) armor and leave no marks on the body. Despite this, they are deadly weapons against most targets. They do not affect machines or daemons however. Those exceptions are telling, because machines and daemons do not have souls like those of normal entities. A semi-intelligent Tau frisbee and a cogitator array have no reflection in the warp. Inversely, daemons are warp stuff itself so do not have souls in the traditional sense. If I had to guess, I would say that the aether blade is attacking the body's connection to the soul. This sounds like it could be Necron, but souls have never been their main area of concern.

Second, Aether weapons are disabled by untouchables, hexagrammic wards, and gellar fields. All these things block the warp and psychic abilities. Coupled with the mysterious nature of the blade and the fact that it does not affect machines or daemons, I'd say the blade is clearly psychic in nature. The Necrons would be the last people to construct psychic weaponry. Anti-psychic weaponry is something else entirely, but this does not seem to fit the bill.

Third, the physical description says that the blade seems to have been "grown" and is made of a "blue-grey" alloy. Now, I don't have the Necron codex to check the description of that Warscythe thing they have, but that doesn't sound Necron to me. Sure, the "blue-grey" part sounds a bit like that, but Necron stuff does not look like its grown. Their technology is a melding of death-imagery, arcane tech, and some ancient Egyptian elements. Although their living metal is a truly strange substance, it seems like it would seem profoundly unnatural rather than something that looks like it was grown. The subtle nature of this weapon also seems to be very different from conventional Necron weapon-tech. Necron gauss weaponry strips the target's molecules away layer by layer. These weapons do not cause subtle wounds.

Fourth and finally, let us examine the closest Necron equivalent to Aether weapons: the C'tan phase blade. They pass through all armor as well. Initially they sound somewhat similar to Aether weapons. Further analysis makes the differences clear, however. C'tan phase weaponry do work on daemons, do leave wounds, and can cut through inanimate metal.

Therefore the only conclusion is that the Aether weapon is not of Necron origin. It sounds somewhat like an Eldar weapon, and their extreme reaction to this sort of weapon tech makes some sort of relation obvious. Perhaps they are used by an enemy of the Eldar, are a perversion of wraithbone tech, are a relic of the Old Ones, or otherwise? There are many possibilities. I doubt Necrons make the list.