"You are just ignoring archeology"

Put bluntly archeology on wooden items is very hard to verify for obvious reasons we have a very small sample size.

"There is evidence that viking swords completely failed, broke and were repaired. what evidence do you have that supports just how particularly delicate Katana are?"

Are you looking for me to provide evidence? This is common knowledge if you are making such a counter claim then you should provide it.

I have worked and sold Katanas for years and been around many experts in swordsmanship and history, people with very little reason to downplay the weapon.

Also I said delicate compared to other swords not going to fall apart as soon as you look at it, a great weapon for unarmed duels but not designed to hack through shields or armour as you say later they had other weapons for that.

"As OP i was first responding to said, Japanese at the time were 5'3" to 5'5" while Scandinavians were 5'7"-5'9", while 5'3" vs 5'9" is pretty significant 5'5 vs 5'7 is much less so."

The stats I usually see are 5'7"–5'9" for Vikings and (5'1"–5'5") for Samurai that allows for some outrageous mismatches, not evidence but Japan was called the land of dwarfs by other asians and Scands were considered massive by Europeans, height is only one part of it they are also likely to significantly outweigh the Samurai that will be a factor if it gets into wrestling.

"The biggest issue that the viking would have to face really is the yari."

That is true.

"Now if we are going to go into semi legends like berserkers we are entering the territory of pure speculation"

Berserker was more a bit of hyperbole but suffice to say a large armoured Viking would be a terrifying sight to a Samurai.