cf. kappa 2121 (and kappa 2128).
This Homeric epithet is applied once to Ares in Iliad 20.38 but is otherwise used only of Hector (38 times). See also Aristophanes, Frogs 818: "helmet-flashing strife".
See G. Markwald in Lexikon des frühgriechischen Epos 2.1490-92 for full bibliography and discussion. He takes the word to refer to the moving of the helmet, dancing side to side in spear and shield fighting. He also stresses the importance of Hesychius’ comment (mu117) that the hoopoe was called koruqaio/los because of the mobility of his multicoloured crest (flat and extending behind or raised high). The adjective may then be taken as referring to the helmet crest. For Mycenaean and post-Mycenean helmets and their crests (e.g. horse-tail crests) see Borchhardt in references. For the much-disputed etymologies and meanings of ai)o/los see alphaiota 253.