Padded Armour

[Robert Vermaat]

Robert has a good point about the weak credibility of the De Rebus Bellicis, you just have to look at some of the most bizar 'inventions' (cattle powered battleships, inflatable bridges, war chariots driven by automatically-lashed horses). It looks as if someone wanted to catch the emperor's attention at all costs, even with a number of hilarious ideas which look like 4th century science fiction.
BUT - the Thoracomachus chapter is one of the few which sounds rather credible, and which is partially supported by later sources (including the anonymus peri strategias from the 6th century).

My point is not so much that the DRB is less credible, but that the whole content is about inventions and innovations of existing equipment. Therefore, I don't doubt the (proven) existence of the subarmalis, but I keep stressing that we should look at the Thoracomachus/Lybian Hide (combination) as something either new, or innovated.
Only, hich part is new or innovated, I don't dare to presume.
If the interpretation is correct that DRB saw the padded Thoracomachus as armour, than I'd say that was the new part. Covering such an armour with a Libyan hide makes sense.
But if this was a padded subarmalis, to be worn under the main armour, as others have stressed, than wearing the Libyan hide under that armour makes no sense at all.