You know, you’re stance in this discussion is currently a very weak one.
Your entire argument seems to be "How do we know KC:D combat is realistic, if its only based off these manuscripts we have [that are most likely what was commonly used], and not actually going back in time to see what people did?"
You keep on saying, essentially “what about other things that were never recorded?” Its kind of like arguing that we don’t know for sure that sunlight comes from the sun because it might come from something else. You see why we keep going in circles 
Yeah, its very likely that not everyone knew all the details, but, as i said before (and this goes to you too, @HolyDeath ), the concepts are simple, and can be quickly taught. This would encourage their spread to everyone - like a trickle-down effect - from the masters, down to the nobles, to company leaders (or their equivalent), to the common mercenary.
To close off this portion, you must remember that this game is trying to be historically accurate. Unfortunately, as with most everything related to history, it won’t be 100% accurate. We have what we know of the time period, and are working off that. The whole “philosophical” side of the argument is more-or-less irrelevant. We simply don’t know exactly how people fought, but we have an educated guess, and that’s enough for the game.
@Warrior_Rose
From what i’ve heard, the locking system is only temporary as they try to get the combat mechanics ironed out - i do think a “sticky aim” would be appropriate, if only to prevent drag slashing like in Chivalry… shudder… However, I must disagree with your opinion that M&B style blocking would be nice - with four directions, its already complicated enough, add in two more at diagonal angles… thats a recipe for panic blocking. I also feel like it would make the combat too difficult. Although i suppose they could implement it through a difficulty setting, similar to M&B… But the devs have enough on their plate as it is.
