6th century AD Roman soldier

[Flavivs Aetivs]

The Anonymous De Rei Militari has been re-dated to the 9th/10th century according to the recent research of Phillip Rance.

This, however, seems to be a bit much, since a daktylos - at least AFAIK - is about 1.95 cm.

Not really. This is about what 25 layers of linen comes out to, which is where a quilted gambeson should be. Other Roman sources mention quilted garments around 2cm thick.

The Peristithridion wasn't the only one. The primary one was the Kavadion, which was a thick, quilted gambeson developed from the Kaftan which by the time of the De Rei Militari, was used for a primary defence mostly.

If you want to find out more about 6th century tactics and logistics, try to get an English copy of the 'Strategikon'. The original book is in Greek, but interestingly the commands are almost all still in Latin.

Shuvakov suggests that the Strategikon may be an update of a work dating to the 5th century attributed to a man named Urbicius. I'd imagine it was commissioned under one of the 5th century military figures or emperors, probably Aspar, but I wouldn't be surprised if it was done under Aetius. I'd have to see if there's any possible candidates for "Urbicius" from the time period.