So last weekend, pre-vomiting bug, I took the family up to see the Higgins Armory collection in Worcester MA.The museum is closing down at the end of this year as it can no longer afford its building, though the collection is fortunately moving in toto to another local museum. Once there I not only marveld at the intricacy of the armor but of how little gaming (and movies and books) prepared me for the reality of people fighting in armor.
When we see heavy armored swordplay (not terribly often) in fiction it is full of heavy strokes and stabs penetrating the armor, and two handed swords being swung in enormous arcs to whack through full plate. The people in the armor are often awkwardly moving and have extreme agility impairments. Then you go to the Higgins and watch people reenact the actual, recorded in masters training journals fighting of the time and it's nothing like that at all. Two handed or bastard swords are held one hand on the hilt, the other midway up the blade so it can be quickly used as a big whacking sword, a short stabbing blade with high accuracy, a blade for draw-cut slashes, a spear, a staff, reversed to hook the enemy's knee with the crossguard or a hammer with the heavy cross-guard and pommel. Try that in your average D&D game and the DM will whack you for 1d4 damage every time you grabbed your own blade, but that's how it was done.
It's amazing to watch, and much of the fight is spent trying to figure out how to stab through the chain mail bits in the armpit, groin etc. because getting through the armor is too damn hard. So people often knocked one another down, climbed over them and with one hand on the blade to guide it drive the two handed sword home through a vulnerable spot. Or got wrestled themselves and both sides reverted to daggers. And then stand up quickly and move to the next person, because the armor is a lot less awkward than you'd think - my wife shared an anecdote from someone who worked at the Higgins that on their Renaissance Dance nights the people wearing the museum's armor were sometimes better dancers and surer footed then the blokes in their garb, so well was the armor made to work with the wearer's movements.
I'm not quite sure why gamers get this so wrong. I suspect part is taking post gunpowder swordplay styles that are more commonly taught/seen these days and extrapolating back in time. Another part is that big whacking swings with bastard swords are cool looking. Those are surely part of it, but another is doubting the technical acumen of the old age - armorsmiths and knights had centuries to work this out, and armor design was the arms race for a very long time. That's a lot of man hours in something that was literally life or death, and they got very good at it, even if the skills were lost when someone figured out a clever new use for bat poop.