The thing that occurred to me about the sword breaking is that there's no way to gauge the quality of the metal work in historical swords, as they said, the "real ones" are all antiques ranging from expensive to priceless. Destructive testing isn't an option.
If you could find 1000 antique swords, especially from the pre-industrial era, and X-ray or magnaflux them, I bet you'd find a certain percentage with pockets of pure iron in them, carbon, micro-cracks, uneven heat-treating, or bad crystalline structures, and those swords would indeed break. .
Now granted there were "masters" like the famed Japanese Katana makers who turned out products that are probably stronger and more resilient than any industrial sword. However those weapons were available to an elite few. The armed masses (when they had swords, instead of pikes, spears axes & bows) would have gotten the swords that multiple blacksmiths would have turned out by the thousands. Flaws would have turned up, and perhaps only in the heat of battle.
There are also specific weapons that are purpose-built "sword breakers", heavy sword-like metal clubs, hooked weapons on poles that could trap a blade and provided the leverage to break it, and jointed flails (think large nunchuks) that were purpose made to defeat a swordsman.
The Japanese police-equivalents in feudal Japan were often armed with such weapons, should they encounter a rouge swordsman...
Granted, Mythbusters was testing the "myth" that swords could be broken by other swords in a determined attack in the movies, but in history, I bet it did happen enough that everyone was aware of an instance in their particular military within someone's lifetime. And it's probably where the movie idea came from.