i worry that this could cause confusion since there is a pokemon named meteor and the nickname for this would make it even more confusing..
I can see where you'd be concerned about calling them "Meteoric" for that reason, although I think you're a bit mistaken. I believe the pokemon you're thinking of is Minior. You're point is definitely still valid though! I'm pretty sure I've seen people calling Miniors "Meteors" as a nickname.
Unfortunately, the two other most common fantasy metals, Adamantine and Mythril, both have roots in other pokemon-related terms (Adamantine could be mixed with Adamant nature, and Mythril could be mixed with Mythical pokemon).
I still like the idea, however, of making the names sound like an upgrade. "Shiny" is a pretty simple concept. "Pearlescent" or "Opalescent" both relate to rare stones. Instead of using a fantasy term, I think using something entirely new or made up by a user would still fit the idea of "fantastical" rarity. "Nyxril" would be my alternative suggestion, a combination of "Nyx" from the Greek goddess of night and "Mythril".
