Sword Fighting is Not What You Think...
To borrow a famous line, the problem with most people trying to understanding the true nature of historical sword combat is not that they're ignorant; it's just that they know so much that isn't so.
...Face it, some readers will really get offended if you dare to suggest that they don't have an accurate conception of sword fighting. Fanboys especially will take it as a personal insult to their very identify when you challenge their assumptions. It's pretty silly, since no one of them relies on this skill for self-preservation nor makes it their profession. Plus, nearly everyone gets their information and opinions on it from the same essential sources: TV, movies, fantasy literature, video games, cartoons, comic books, dinner-theaters and renn-fairs fight shows. But where do those sources get their notions?
Almost entirely from experience with sport fencing, Asian martial art styles, and pretentious historical role-playing societies. Yet, all these sources derive their conceptions of it from still earlier ones. And so on and so on. Where then did most of today's ideas on historical sword fighting originate? When we trace it all back, we find romantic beliefs about the nature of swordsmanship among knights and cavaliers almost all started with ignorant Victorian-age prejudices.
Fortunately, during the Medieval and Renaissance eras there were produced hundreds of detailed instructional manuals by expert Masters of Defence. These knights and professional instructors in arms wrote and illustrated immense technical treatises and books on their "science of self-defense." Intended to preserve their secrets or instruct their students and patrons, these little-known works, some in excess of six hundred pages, represent time-capsules of the actual fighting systems and proven combative disciplines used at the time. Focused mostly on swordsmanship, these handbooks and study guides reveal highly sophisticated combat teachings. Further, their content and presentation is unmatched by any martial arts literature from anywhere in the world.
...And we have dozens of them...
In the end though, the piece can be summed up as "why don't filmmakers hire people who really know how to swordfight to choreograph their movies some times? And when I say 'people' I mean me."