Nilpaurion has the elements
paur, fist, and
-ion, son.
I don't know what
Nil means. Although I think it came from
-(n)dil, lover of, devoted to.
As for
Felagund, well, I needed a surname. Finrod is great - no, wait. He's the greatest. And he has no son. So I pop up.
Amarië, it's me! Your son!
I don't have a son.
Great. Thanks a lot, mom.