Xenophon's On Horsemanship Neck Guard

[Giannis K. Hoplite]

Yes, still, the point is one cannot put them over the jaw, like a pullover. Otherwise there would not be a need for an opening at the back.

To me this means one of three things.
Either Xenophon is talking about something different altogether,
Or these gorgets had some variations that allowed the covering of part of the face,
Or these gorgets can be moved in some other way when worn that offer protection to the face. Look at your second gorget for instance. It has hinges, presumably for easy wearing. Maybe these hinges allowed the front part to be raised when worn?

However Xenophon says also two interesting things: that the gorget can act as an ornament, and indeed many of these gorgets are lavishly decorated with gold, and there are even necklaces from Thrace with the same shape, and that only "if properly made" the gorget can cover the face. This is an indication that oftentimes these gorgets were not properly made according to Xenophon.