I've seen these referenced a couple times in the book, in one of the charts dealing with making daemon weapons, and under the Flesh-Fused Weapon details, but can't find any more about them.
I'll admit I've only really been skimming around the book, but it's not even in the index, and you'd think being referenced like it's important would merit a spot there. I can't even find more than those two above mentions using the search function on my .pdf copy.
So I was hoping someone who knew better could help me out here?