I'd like to glamour old versions of the relic weapon

Add a vendor that lets us buy statless versions of previous relic incarnations so that we can glamour them back to the way they used to look?

You can repurchase un-upgraded relics from a Calamity Salvager already, if that's what you mean.

you can via by the calamity salvager, it's only the base i80 relic, no zenith or anything.

OP is likely referring to being able to buy Atma, Animus, etc. from the vendor once you've moved past that stage for that specific relic. The alternative is re-grinding them to that state.