[Gil-Galad]

another reason could be Echthelion

Balrog's bane- killed Gothmog, lord of the Balrogs
Came back again- the stewards of Gondor took his name, so he was kind of reborn
Twice aided a flight, from the forces of night- well, back in beleriand he helped get Gondolins troops back to Gondolin and stalled aganest evil forces in the courtyard
Person of might- described as an Elf-lord of the Firstborn, who has dwelt in the Blessed Realm.
Clad in white light- Elf-Lord! pretty strong!