Here are the etymologies you requested:
Manwë = "Mr. Perfection," i.e. Matthew Arnold.
Language: Quenya
Two elements: man (shortened form of "aman" = "unmarred, perfect") + we, an
element found in many personal (usually masculine) names and derived from a
stem meaning just "person."
Gwaihir = Wind-Lord
Language: Sindarin
Two elements:
gwaew, "wind," from a primitive Elvish stem wâ-, wawa-, waiwa- meaning "to
blow"
hîr, "master, lord" from a primitive Elvish stem kher- "to possess"
Elrond = "Star-Dome"
Language: Sindarin
Two elements:
el - "star"
rono "to arch over," yielding rondô, "vault, dome"
I have no idea if any of these were designed to give a "double etymology" in
another of the many languages which Tolkien knew. Somebody else posted
about Meriadoc, that it was Welsh. I have no Welsh, so there it must
rest.
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All that is gold does not glitter,
Not all those who wander are lost;
The old that is strong does not wither,
Deep roots are not reached by the frost.
From the ashes a fire shall be woken,
A light from the shadows shall spring;
Renewed shall be blade that was broken,
The crownless again shall be king.
