The arms, equipment and impact of Late Roman Clibanarii

[D B Campbell]

It would be great if somebody with a real knowledge of classical Greek could comment on this.

Until we find such a person, may I offer my support for your interpretation, Jens? The translation which is available on the internet (Wright's 1913 Loeb translation) is not quite accurate, as you spotted.

I would even (tentatively) suggest that, for poetic effect, Julian first mentions force A (οἱ θωρακοφόροι, "the cuirass-wearers") and force B (τὸ λοιπὸν τῶν ἱππέων πλῆθος, "the remaining multitude of horsemen"), then reverses the order, mentioning force B (οἱ μὲν ἐκ τόξων βάλλοντες, "some shooting from bows") before force A again (ἄλλοι δὲ ἐπελαύνοντες τοὺς ἵππους, "others driving-on their horses"). Just an idea, and certainly not necessary to support your conclusion, Jens.