It looks like the pince-nez tag doesn't have any implications associated to it, so before doing anything, what do you all think the relationships, if any would be?

Suggestion:

implication pince-nez -> eyewear

And possibly to glasses, but they seem to be in a distinct category of eyewear

Agreed, imply eyewear but not glasses.

Hm, they should imply both, seeing as they are used as a type of glasses for reading.
However, only implicate, all of the pince-nez are glasses but not all glasses are pince-nez.