Board Thread:Suggestions forum/@comment-43807312-20190916075023/@comment-43810165-20190917025124

Virgil and Luine are right as it was the First-Age elven swords that turned blue. More specifically the ones from Gondolin before it fell to Melkor. Due to the destruction of Gondolin, obtaining one in the Third-Age was a very rare but high-prized thing in Middle-earth. Gondolinean swords (hope that's the correct adjective) were also known to last for a very long time without becoming blunt or getting rust on their blades, making them even more value. The few blades that made it to the Third-Age include Glamdring, Orcrist, and the dagger Sting.

I do agree with the OP that they should make the elven swords more close to the books. But it could be in the books, and it has been a while since I read them. So there might be an odd paragraph that actual states the elves' swords do glow. It is also possible that the elves had not lost this luminous knowledge (sorry) and still incrafted it into their swords long after the First-Age.