I'm planning to use Dark Eldar in an upcoming game, and I noticed that almost all the Dark Eldar have the Dark-sight trait (Archon, Succubus, Haemonculus, Wrack, Grotesque, Incubus, Mandrake, Kabalite Warrior, Scourge, and Reaver.) The exceptions are the Wych and the Sslyth. Sslyth make sense, as they are a separate species of xenos rather than Dark Eldar themselves.
Wyches, though... This must be an oversight, right? I don't know of any fluff reason that they would be the exception to the Dark-sight rule, and yet they don't have it.
I guess this is less a question (I'm giving them Dark-sight), and more a "Hey, don't miss this when the Living Errata is updated for Enemies Without."