Wait, why is the host a factor in this? By far the easiest way for Fallen to end up in Demonreach is for Harry to chuck the next few coins he retrieves off of dead Denarians into the back of one of the tunnels. A live host is going to be putting up one hell of a fight, but scooping pocket change off a corpse is comparatively easy.
Wrap them in whatever blessed container it takes to prevent other Denarians summoning their comrades' coins back, leave a sign "Future Wardens: Do Not Touch", and basically forget about them. Whether they're meant to be in circulation or not, that's a free-willed mortal's choice to put them well beyond reach of anyone else.