and the identity of the poor Red Devil that Allison stole the mask from be the one in Princess now? And for that matter, what ever happened to the Red Devil whose mask was taken off?
As seen on this page
http://killsixbilliondemons.com/comi...of-names-1-13/

Then clearly a devil mask is slowly worn down over the years, at some point needing to be replaced.
In the background we see the trio of magisters bartering with said devil for what clearly seems to be a new replacement mask.

So i guess the answer is, nothing. That mask had not been in use before, and the red devil still needs to get the replacement mask it bartered for.