The Roman Centurion armor, is simply chainmail. Knight's armor is simply steel. All of it is medieval. Imperial Legion armor is a lot like gladiator armor. Viking is also chainmail, and I would assume that fur armor would also be viking. Elven, Orcish, Daedric, etc are fantasy.
:facepalm:
Sort of. Roman legionary/centurion armor was not chain mail until second century a.d. The typical armor you think of when you picture a Roman soldier is called the lorica segmentata, and was not mail, but iron stips placed horizontally over each other to provide good defense, but be compact-able.
And the Imperial Legion armor is in no way similar to the gladiators. There were many types of gladiators, usually with little armor, or very stylized armor, and the guard looks like none of them.