This is a tangent that occurred to me after coming up with the post linked above.

The premise is that when a full fledged channeler ie a Sovereign dies (fails to use their magic to escape) a part of the personality and the Essence is imparted upon an item in close proximity to the dying character. Examples could be a family heirloom or even the weapon that was used to kill the channeler. The "soul" can then choose to bond with an appropriate vessel...which would probably not be the killer!

So, at the beginning of the game you're a latent or partially awakened channeler who happens upon an ancient relic of one of the titans or mages of yesteryear and is chosen to be given the boon of the ancient's power. You could have a cool cutscene or intro of this experience depending on what kind of character the sovereign is such as a dark and forbidden cave full of undead or demons in the case of a death mage or the last living tree of an ancient grove for an earth mage or slaying a powerful warrior and claiming his sword for a knight.

In the game then it would be possible for one of your heirs to recover your essence and become a blend of you and the heir. The better the connection between the dead channeler and the new host would relate to how much power was effectively transferred if for example you had to rely on a random adventurer the transfer would be poor leading to a major loss of power rather than a blood relative with similar personality.

Thus, death of the sovereign would be bad but not unrepairable and would add to the roleplaying element of the game.

To go with the previous linked post then you could create a starting character following the rules for NPC's and then "happen upon" the ancient relic and gain the essence and descriptors appropriate such as Sovereign and magic. This would make the rules for NPC's and Sovereign basically the same with just an addendum rather than having different systems for development/character creation.