Soul lamps were uniquely special items. On the one hand, any Clan worth almost anything would have some, even those too insignificant to be considered minor nobles—Clans that didn't quite have true noble status, but had made their way in the world in other ways.
But, on the other hand, they could scale to shocking degrees.
The vast majority of soul lamps could only work within certain ranges. Because of this limited range, it was hard to tell when or if someone died at all unless they did so within said radius. If an important member of a Clan planned to leave this range, they would often have to take an amplifier of some sort with them.
There were many cases of such members of Clans leaving for too long, causing their soul lamps to extinguish. If they ever returned, they would have to reignite them.