Maybe Gen traded his life for his coin, Hades is one of the few who could keep it safe.
The nature of the coins is to get back into circulation, but we currently have one sword without a wielder, one third of the coins might not be able to get back into circulation to maintain balance. In addition the nature of the faithsabre has drastically changed one of the swords, this might to affect the coins as well, and this occurred after Gen got iced.