Economic migration is nothing new. Technological development in Scandinavia meant huge population growth. They went looking for adventure, loot, land and status. Their own sagas tell as much.
Somerled, the forerunner of the Lords of the Isles, was named such because he was a Summer Viking
Once the crop was in he went raiding. By the time they'd been there a couple of generations and married into the locals, (we call them Galgael....strange or foreign Gael, mixed Scot and Viking) they just expanded their trading networks, adopted the local religion, much of their authoritarian structure and started bitching about having to pay taxes and still owe allegiance to the old kings back home in Scandinavia.
Sound familiar ?
Most folks of the time died of disease and malnourishment.
Pole arms are incredibly effective in pre gunpowder battles. Shiltrons took down the charges of armoured mounted knights. Once the knights were down the men at arms simply butchered them.
At the end of the day fitness, strength, force of numbers are one thing; the reality under discussion by the OP is the constraints imposed upon the general public, in attempts to restrain the ability of a few to cause violence with knives.
Most folks here aren't bothered by the constraints, they really aren't an issue for most people.
'Here' being in the central belt of Scotland in 2013.
cheers,
Toddy