On p136 of Edge of the Abyss it is mentioned how one NPC plunged a black crystal shard in the heart of his adversary. That man was then transformed in a vile blasphemity with alien hungers. The shard was a halo artefact. It is then mentioned that the artefact comes from the Yu'vath.
As far as I'm aware, there has not yet been an official link between Halo Artefacts and the Yu'vath. Or did I miss that one? I am more familiar with Dark Heresy than with Rogue Trader.
Curious to your views!