I don’t find this all that impressive after closer study. First the ball was aimed at where the sword would be, so all the guy had to do was begin to draw the sword and the ball would be sliced in two. Second, the intent to draw the sword has to precede the firing of the ball, because you correctly point out that human reaction is physically limited by the speed of neural processing and action potential conduction along the nerves. Third, you haven’t seen the 10 or 20 or more failures that preceded this acceptable result.
That it takes considerable practice — and failures — to achieve this performance in no way diminshes the success. A pianist practices for weeks on a piece. A golfer drives thousands of balls and putts, and not every one of them goes where he wants. And show me any athlete who doesn’t practice.
The ball is indeed fired at where the swordsman will strike, but a pitcher throws at roughly where a batter will swing and the batter misses the pitch more often than he hits. He’s a lot farther away from the mound than 30 feet and few pitchers can consistently throw at 100 mph. And a batter doesn’t have to draw his bat from a scabbard, then cock and swing; he stands at the ready.
As I pointed out, the swordsman cut WITH the ball’s flight, not against it.
This is a remarkable accomplishment, any way you “slice” it.