I remember watching a martial arts "master" conduct a class in front of an audience where all he did was wave his hands, and scores of his students immediately fell to the ground.
When these students regained their strength and tried another way to combat the master, all he needed to repel any attack was another simple wave of his hand, and again the students crashed to the floor.
On the surface, it appears that the martial arts master's exhibition was meant to deceive the audience, that he was faking his special invisible powers allowing him to neutralize would-be assailants with a wave of his hand.