Well I'm going to have Eldar be a part in my game coming up, and I was thinking about using my limited knowledge of Tolkien's elvish to make the game feel more real. I think it would be cool. The term Eldar is in The Lord of The Rings anyways.

Oh and its Quenya sorry about the typo.

It could absolutely work although you might want to take a look at some other Eldar phrases and modify your elvish accordingly. A direct transition between the Middle Earth elves and the Eldar in 40k may or may not work thematically.

Not saying its a bad idea, because it isn't, but just want to give a notice.

To be honest those are good observations. I can get my hands on the Eldar codex prior to the one that jusr came out. Do some brain work. Thanks