I am sorry, it had been a couple of days and I lost track...but I disagree with you on the diet of the knights...it was not always “excellent”, knights were not at a level of a king or queen, nor not necessarily the upper echelons of royalty who were relatively immune to famine. In any event, there were periods of severe famine that were regional...these caused different heights during the same time period for different regions. The variance would make an “average” hardly meaningful when trying to extrapolate that to “proving” the Shroud of Turin is a fake.
I am not at this time arguing the armor issue you brought up. I will perhaps later after I have spoken with my son who is a historian/archaeologist who specializes in the medieval era. I do wonder where you got your information regarding the “discovery” that the smaller armor was youth armor rather than for smaller adult individuals. Armor was very expensive in relative terms, not something one would dabble in. I would think youth would be much more likely to wear leather and/or chainmail or woven armor.
I used to collect edged weaponry (actually, I still have a bit) and read well on the subject of arms and armor. Adult armor was generally used through out the adult's lifetime and was added to, repaired, replaced, etc., but seldom retired to a place of display. Not so armor that was outgrown. At worst, outgrown armor was handed down to a younger brother... but it would still be retained in its entirety, not scrapped and melted down as was the worn out armor of a well used lifetime of an older man that had seen numerous battles.
The relatively unscathed training armor of a cadet was more suitable for display and was retained. The old, often mis-matched, scarred armor of the elders was sent to the armory for either use as replacement parts or to be smelted down and remade... but only the Armor of Kings was likely to be retained for display... and the armor of the cadets that could be handed down but could also be displayed because it matched and was not scarred.
One of the strange thing noted among collectors was the dichotomy of the length of the surviving fighting swords and the size of the display armor... with their swords... they didn't match. The fighting swords were longer, man sized, while the display swords and armor were more aptly sized for teenage boys. The question arose why rusted swords found on battlefields and swords kept in racks in armories were longer than those found on display with a lot of complete sets of armor... this is one logical answer that seems to be true.