Each crescent blade that he made is thin and almost invisible if not viewed from the proper angle. The only way to see them is to be situated in a position where you can see the flash of light reflected off of them. So it looks like he is not doing anything to some onlookers. Then he stopped all of a sudden and watched his work.
The first crescent blades of power were slow while the ones that came after them are faster. Each subsequent crescent was released at a faster speed than the previous ones. So they were bound to overtake the ones before them. He timed the interval of release and their speeds such that all of them overtook each other at the exact same spot and at the same time. They were effectively superimposed on each other at that point. It was then that they could be seen.
