/Trump will speak in parables or metaphors.
I noticed that he will repeat a phrase 2-3 times. He also holds his hand up with the thumb and first finger in a circle, the other 3 fingers upright. It is very much like an old orthodox rabbi making a point with repetition and gesticulation. It’s very interesting to watch.
The Trump hand gesture you just described is seen by artist Scott (Dilbert) Adams as a discreet method of crowd hypnosis.
Who knows. There may be something to that. In many cases, the upraised hand does become a sort of swinging amulet, metronome or focal point while certain conceptual phrases are softly repeated and thus ingrained. Public Speaking is about a lot more than just talking loudly and reciting a script. All three presidential candidates (Trump, Hillary, Bernie) were effective in their own ways, some, obviously more effective than others.