The lost medieval sword fighting tricks no one can decode

Even in some of the martial arts that have a fairly continuous tradition, such as karate or wing chun, there are often debates about what the different moves in kata/forms/patterns actually mean.

I've seen people come up with all sort of crazy and completely impractical 'applications' of karata kata moves.

I also remember being told a move in the first wing chun form is a jab to the collar bones with the finger tips (completely impractical). Then one day a master come from Hong Kong and told it was an eye gouge with the thumbs (very practical!).

For example, most of "modern" wushu (so called kung fun) styles disappeared in the last 60 years starting from the Cultural revolution and ending last fifteen years, where in some families grandfather, father and son died one after another in a couple of years.

But the real reason is a lack of cultural context. No one needs to spend four hours a day training to be able to earn a living using violence anymore.