[Saurreg]

The armor of gondor does look like the mail and plate sort from the fourteenth century.

The books stated that some of the Rohirrim wore Gondorian designed armor and were hence better protected than the Dunlendings. But in the movie, they were wearing chainmail armor that was more akin to the late dark ages and early medieval era.

I have personally always thought that Gondorian armor was more like that of high Byzantine ( i.e. lamellae and mail) than late western medieval.

Edit: The helm type used by the Gondorians is known as a barbute. That together with the design of the ornate cuirass makes the Gondorian man-at-arms extremely Italian in appearance!