I was just reading u/n7fury's post about the use of shields in Medieval Japan and it got me wondering.
There are the ubiquitous portrayals in media like Game of Thrones, etc, which mostly depict the sword being held around waist or chest level and combat being confined largely to the "close enough for a sword, not close enough for a punch" range.
In my experience, this is by far the most common depiction. But a couple of conflicting descriptions stand out to me--I watched Kingdom of Heaven recently, and one of the scenes that stood out was when Liam Neeson was teaching Orlando Bloom how to fight. Bloom put up the standard waist-high posture described above, and Neeson corrected him, holding his sword in two hands above his head like a sledge hammer or pickaxe. I also recall reading Michael Crichton's book Timeline some years ago, in which he describes combat between knights as being extremely physical, with lots of grappling, punching, kicking, etc. and less emphasis on weapons than is commonly depicted.
Which brings me back to the question: do we really have any idea how medieval knights really fought? Are their written descriptions or even training manuals, or reliable and consistent illustrations of man-to-man combat? If so, did the method tend to be the same across regions/times/weapons/individuals? Or were there a variety of styles employed during the medieval period, either simultaneously or in distinct waves?
We do, in fact, have "training manuals" of knightly combat. Quite a lot of them, actually! They are called "fechtbuch" in German, and taught grappling, longsword (both in and out of armour), mounted combat, polearms and more. Some of the more famous authors of those manuals include Hans Talhoffer, Fiore dei Liberi and Paulus Hector Mair, but there are many more.
As for what the combat would look like, there are people out there who are using these manuals to reconstruct Historical European Martial Arts (HEMA). This is what unarmoured combat would've looked like: www.youtube.com/watch?v=aBGB8ngvggs And armoured combat: www.youtube.com/watch?v=G4k-vjdeZO4
As you can see, in armoured combat, they don't even hold the sword normally! They fight in a position called the "half-sword", in which you grab the blade with your left hand so that you can stab more accurately, but there is a lot of grappling, and a lot of those fights probably ended up on the ground.
As for styles in the late medieval era, we have 2 popular traditions: the German Liechtenauer tradition, and the Italian Fiore tradition. There is evidence of other styles existing, but there is less sources on those, and so they are hard to reconstruct. Most of the historical masters taught multiple weapon types under one system.
tl;dr We have medieval fight books that show us how people fought back then, and there are people now who are reconstructing those martial arts.