I suppose the difference is in what we mean by Arthur's Era. Movies like Excalibur, for example, are based on 13th century French romances and thus the entire technology and culture represented is much later than the late Roman/ 5th Century. If this theme park wants to represent Arthur wearing plate armor and carrying a broadsword, then I would say all of Peg's suggestions are good ones, and this is likely to be what the theme park wants. If, on the other hand, they want to represent Arthur as a Celtic chieftain, then something older would be better.