Suggestions for best use for an extra Brilliant Viridian Key

[RavenTwospirit]

So wouldn't you just know it . . . I bought myself a Brilliant Viridian key from the NCoin Store after giving up on the RNG for getting my Blighted class weapon. I ran Blackram Narrows one last time to get a lockbox to open, and of course that run my class weapon dropped! So I didn't need to use the key after all.

 

Since the keys are not tradeable . . . what should I use it for now?  Any suggestions?