The instructor standing nearby lends confidence before the skill can fully supply it.

Before a skill is reliable, something else has to hold you up, and often that something is another person within reach. The instructor rarely does anything; their standing there simply removes the worst outcome from your mind so your hands are free to learn. Courage borrowed like this is not a weakness in the learning, it is part of the mechanism. Later the competence takes over and the presence is no longer needed.

While you are learning something, ask someone to be nearby rather than trying to prove you do not need them. If you are teaching, stand close and say little. Presence does most of the work.