I really love the complicated but compelling story you've put at the heart of this spark where none of the parties are fully in the right or the wrong, which of course allows the players to truly choose and form their own opinions about it. I also love the mechanics of the obolos and how the players can learn to avoid death through dubious means and real consequences.
I did wonder about the 'if the Obolos is stolen, Iomaire’s authority remains, and no other being wants to infringe on the soul, leaving it in the control of the bearer of the Obolos' ... what happens if other beings do want the soul for whatever reason? Or is that just an absolute law of the Rites of Iomaire, and Iomaire will always have claim to it?