@Haerangil When and where would you propose Enerdhil taught Celebrimbor, though? Celebrimbor was the less skilled, but surely he initially learned is crafts from his father and grandfather. If you mean after Feanor's death? Enerdhil lived in Nevrast > Gondolin, but Celebrimbor lived in Himlad > Tol Sirion > Nargothrond > Doriath. They would have met again at the Havens* and could have lived in the same place in the early 2nd Age -- is that where you want them to meet and make friends? Enerdhil could well be one of the Gwaith-i-Mirdain. I had thought (though I can't cite a book for it) that Pengolodh lived in Eregion for a time.
*Unless we use MithLuin's proposal to merge Enerdhil and Rog, and kill him off since Rog died in the Lost Tales.
Galvorn was made of a "falling star" (meteor??) so it might be a sort of iron-nickel-
something alloy rather than a magical element unique to Arda. Then again I think
mithril is titanium, and I know many consider it wholly imaginary.
@amysrevenge We could decide that Erestor was from the First Age. But I think it's saying something that Elrond was made a general when he is, apparently, mainly a healer instead of a fighter. I don't think more than a handful of First Age Elves were left in Middle-earth by the end of the Third Age.
They did die out and leave gradually, though. In the Second Age there're Gil-galad, Pengolodh, Celebrimbor, possibly Enerdhil early on, and Cirdan who stays longer. We can include potentially any lord of Gondolin who didn't die in the sack of Gondolin nor at the Havens (so Galdor and/or Legolas, plus Glorfindel) or change the fate of one of those who died in the Lost Tales (Duilin, Salgant, Egalmoth, Penlod, Rog). Am I missing/forgetting any others? I do want the sacks of various fortresses/cities to kill multiple named characters to make it feel more tragic.