Maximum options. Certain eras give a range of options. if you want all the medieval options available then you have to go to the very next era: the renaissance. All the armors and all the great weapons are available unfortunately they are all obsolete.
Then there are eras where certain weapons and armors reign supreme. Armors and Weapons have an interconnected relationship. Advances in Armors seem to influence weapons more than the other way around. Mail seems to be one of the best armors but the hardest and the most wasteful of skilled labor resources (because it is incredibly repetitive). Other armors are almost as just effective if not better is some areas. Scale is effective, more effective in some areas and is easier to make but has comfort and weight issues. Lamellar has many great strengths, but is pretty complicated to make and maintain. blah blah blah
Anyway, doing some little research a part of my compulsion.