Thanks for the reply, I appreciate it - especially when you bring such an interesting source with you. I've not read that one before, but it's a good one and might be of some significance to roleplayers of mages. This sentence in particular could be a revelation in and of itself:

Further implied is the idea that souls occupying the construct are always sentient—the souls of men or mer—a fallacy perpetuated by the practice of animating corpses for martial or manual labors.

On the subject of Soul Gems and how Molag and Marco work together (alas, still not played the game), I enjoyed this sentence from the book On Soul Shriven:

With the Daedric machines working constantly to empower the portals and drive the cogs that control the anchors, it is no small surprise that Molag Bal requires so many thousands of soul gems. Each one passes through my castle sooner or later for inspection, some bearing unusual qualities depending on the individual trapped within. Indeed, those whose souls were condemned to Coldharbour through the sacrificial ritual tend to display these gem qualities more commonly than others, and it should be little surprise that they contain more latent power than "simple" black soul gems.

I think for the first time we're seeing how ritual sacrifices do increase the power of the spell, something hinted at before but never spelled out iirc.