Painted Helmets and repainted Linthorax

[Feinman]

I very much suspect that some of the patterned geometric bands seen in the depictions are actually tablet-woven bands; they are often seen near the top of the tube section of the armour.
Some of the other decorations could be embroidered or painted.  Much earlier Egyptian linen armour had tablet-woven bands, as did some of Tut's garments.