But on the other hand, one should be conscious of their environment: The cutting board, about as small as can be; the table, distinctly glass, a material that hates nothing more but shock; the ‘swordmaster’, clearly having never done such a thing before, etc.

It doesn’t take a genius to guess what could have happened. Even if it did survive the initial impact of slicing through the watermelon, anyone could see that the force of the scimitar on the table would surely shatter the glass, despite having a small cutting board underneath. Your comment about knives being handled by dolts is on point.

After looking at the video a lot closer I can see that I’m wrong about the geometry and the blade did cut the melon, then busted the table top but I Stand by the remainder of My statement.