Winged helm

The winged Helmet originated with the elves and was worn by noldorin Warriors, especially the fighters of the House of the Wing in Gondolin.Later it was adopted by the Edain and their numenorean descendants.Late derivations of the winged helmet were still worn by the gondorians, specially the Guard of the Citadel of Minas Tirith.

speculations
Tolkien´s description of the winged helmets of the gondorians and elves seems to match his sketch of the crown of Gondor, shown by him as being based on a tall helmet with wings attached.Tolkien was inspired by egyptian crowns as the Hedjet, but maybe also by historical helmets as the Assyrian helmet, the conical helmet and the european bronce-age pointed helmet.