Full plate armor only weight about 30-35lbs and was extremely maneuverable. As far as sword steel goes then while some modern steels are superior as far as edg

Full plate armor only weight about 30-35lbs and was extremely maneuverable. As far as sword steel goes then while some modern steels are superior as far as edge retention and or corrosion resistance goes they aren’t that much better than some of the ancient high quality steels as far as the final product goes to appear magical. Modern blade steel is more about mass production and consistency so you don’t need to hammer the impurities for 50 days out of your billet. Sure you might be able to go with titanium instead of steel for the armor but I’m not actually sure it would provide better protection. Plate armor was tempered steel it provided protection by deflecting blade blows and by being able to absorb crushing blows trough deformation instead of shattering. Yeah you could design a full plate armor with composite materials today that might be better but then it’s well beyond modern steel and even then I’m not sure if many people would think it’s magic.