5’3-5’10. Where do you get that figure from? Have you seen a real life set of samurai armor from around 500 years ago? It’s pretty small. When I say small I mean you look at it and think of 8 year old boys with swords. Small. 5’10 is not a possibility here.
First off, splitting a helmet like in that link is an incredibly poor test of swords under battlfield conditions. The man in the picture is getting every condition to its absolute perfection and still getting wounds which were quite possibly survivable (the level of brain trauma involved would have been minimal).
Ok, here is the relevant factors:
In nutrition, skills, training, and every human element, the two sides are closely matched.
In equipment, the matter starts getting more confused. The samurai has a better bow, but it’s a type which doesn’t work that well in Europe (environmental conditions).
The knight, particularly later on, is nigh-invulnerable if given the best quality armor (which is fantastically expensive, but still). Japanese armor is works well against their weaponry. It’s not clear how well it would function against axes and heavy spears; contemporaries apprently felt it was worth wearing but not something to rely on to save your life in such cases).
The katana is unlikely to come into play. It was a decent cavalry saber or duelling weapon made under conditions of inferior iron, and that was it. Various european military swords are much more useful against heavy armor, as they use the chop motion; sharp, curved blades tend to be better against light or no armor conditions, which this is not.
Both may wind up in a spear-fight from horseback, which would be interesting.
However, I ultimately give the knight an edge only because of shield use. The Japanese have almost no records of shields in combat. They are, however, an incredibly useful item and were used by virtually every other military in history before guns, and even long afterwards.
Again, shields, specially kite and heater shields had long fallen out of favor by the 15th century.
Articulated plate was being mass produced at forges through out Europe and was much less expensive than in earlier times. Given it’s incredible ability of keeping the weapons fo the time at bay, soldiers and knights opted instead for more versatile and accurate two-handed weapons. The longsword being one, the spear being another, but pole arms were also very popular.
I’d like to say that I’ve never seen any evidence that the Japanese ever made armour of wood. Lacquered leather and iron, yes, but not wood. So a cite, please, from those who mentioned it?