We previously saw the Demonic Smartsword Prototype, which uses some of Boundless Hunger's DNA, in episode #666 of the series:
I remember making a theory where if the Demon Swords reunite in spirit and reform Pandemonium as a ghost, they could use Boundless' connections to the new Smartsword to possess the people who buy and wield them. And we can assume that a lot of people are gonna do just that.
