Illustrations of Sassanid Persian Clibanarii

[Urselius]

I have no problem with any of that but I still don't think that it deals with Dan's point about plate being worn over mail.

Yep. Nobody has produced any evidence for plate or scale armour being layered over mail during the time in question. Even in a Byzantine context there doesn't appear to be anything dating before the Middle Ages.

No outright evidence, certainly, but there is a problem with the apparent inequality of armour provision between the limbs and torso in descriptions of cataphracts. Why armour the limbs with plate, if you leave the torso with mail or scale? The Romans could and did make full length mail sleeves and chausses would have been within their abilities to fabricate. However, they used plate for cataphract limb armour. The real advantage of plate over mail or scale is that is deflects rather than traps points and offers protection from percussive injury. If the Romans wanted to protect limbs from these dangers why leave the torso without similar protection?