Trajan\'s Column V Adamklissi

[Tarbicus]

had no eye for military detail

Or they just didn't care about accuracy of details? It is quite conceivable that the story/characters mattered more than the specific details of equipment.

Absolutely possible, much like Hollywood today. But, why the accuracy on other details? Could it be because they were still available as reference, perhaps from Praetorian guardsmen, but a legionary in the Dacian Wars was not, within Rome itself, and thus the written descriptions of those things not readily available were interpreted from books, or left to the memory of an adviser who was there?