A flame of fire (phlox puros). As in the opening vision of Christ in Rev 1:14 (Rev 2:18).
Many diadems (diadēmata polla). A new feature, but the dragon has a diadem on each of his seven heads (Rev 12:3) and the first beast one upon each of his ten horns (Rev 13:1). So the victorious Messiah will wear many royal diadems and not mere crowns, because he is King of kings (Rev 19:16).
And he hath (kai echōn). Nominative active present participle of echō either used absolutely as an independent verb (like indicative) or in an anacoluthon, though autou (his) is genitive.
A name written (onoma gegrammenon). Perfect passive participle of graphō as in Rev 2:17 (cf. Rev 3:12).
But he himself (ei mē autos). “Except himself” (common ellipsis of the verb after ei mē, “if not”). See Rev 2:17; Rev 3:12 for the new name there described. See Rev 14:1 for the name of Christ on the forehead of the 144,000, and Rev 17:5 for the name on the forehead of the harlot. This word here supplements what Jesus says in Mat 11:27.