One thing that gets me in every forum for every game I follow, such as Skyrim, Chivalry, War oF Roses, For Honor, etc, is the computer nerds are allways comparing the weight of weapons and armor to thier own abilities and strengths. The millitary trained soldiers drafted into the army would be trained in the correct usage of these weapons and over a short time thier bodies get stronger and they move more effeciently. A trick my sensei would do is if anyone complained that their boken was too heavy, he would give them a large hard wood 4x4 in the shape of a sword, it weighed about 8 kilos. Then he would ask them to practice thier kata with it for a few mins. Then he would give them back thier boken and tell them to do it again. Straight away the student is making blinding fast and accurate strikes. They stop complaining about the weight after that.
My father loves researching medieval history and read much literature about the armor they would wear and the weapons they would use. He explained to me that the full set of knights armor was customized and built specifically for that knight, to fit him exactly to his his body and size. The richest knights would have thier own black smith craft thier armor specifically for that knight, and in it it would feel as natural to wear as thier own skin. Soldiers and knights would be wearing this one set of armor for weeks without taking it off as they traveled on thier campaigns so the armor had to be made for comfort and easy to move in.
1.5 KG is nothing, thats as much as a block of cheese, I used to practice boxing with 5kg weights in each hand (got the idea from dragon ball Z) so 1.5 KG is practically weightless to some one who would be trained in medieval warfare. At the museum in my city they have a 2 handed sword on display, it was about 6 feet in length (inc grip) and some other 2 handed swords, but the blades them selves were thin and flexible, they looked nothing like the thick iron swords we see in games.