The origin of the word \'Clibanarii\' solved?

[Renatus]

σιδηρᾶ καλύμματα, which are surely "iron hoods"

Liddell & Scott defines κάλυμμα as 'head-covering, hood, veil', so σιδηρᾶ καλύμματα could, perhaps, extend to helmets covering the whole head, with the face protected by a solid mask or mail.

[Nathan Ross]

A ridge helmet or spangenhelm is technically a bunch of big "plates" of sheet steel, could he really just be talking about a helmet?

Although Heliodorus (Aethiopica, 9.15) describes his clibanarii wearing "a helmet which has been compacted and forged in one piece and skilfully fashioned like a mask into the exact shape of a man’s face".

This suggests something more like this (which gives at least the impression of being 'forged in one piece') rather than either a segmented or ridge helm, or a mail/ scale coif.