Short end of the stick, so to speak...

[the mortal elf]

Where do you get this notion? Where does it say?

I'm not quite sure of the exact place, but isn't it implied in the Sil that the Glorfindel who fell fighting in Gondolin was the same one (born again) who saved Frodo in FotR? Maybe I'm just imagining things, but that's what I seem to remember.