You are now facing a man whom you want to arrest. If you move directly toward him, in an attempt to seize him, he could easily make use of whatever weapon he has concealed on his person. You should, instead, stand in the left hanmi and, swinging your left hand upward to a point in front of his face, stop his motion with your flow of ki. You need not actually strike his face.
Although, since your left hand comes straight toward him, he will think you are going to attack him from the front, you must actually move to the left as you advance in order to get your body out of his line of attack. In the next instant, move rapidly to his left rear and, following the procedure in Arrest Technique 2, seize his elbow and apply a sankyo hold…
The reason for the upward movement of the left hand stems from the principle that the spirit controls the body. By suddenly thrusting your hand in front of your partner’s face you instantaneously stop his spiritual current and, as a result, his physical action.
This coincides perfectly with several of the central points I stress in the “Zone Theory of Aikido”. With regard this particular point, I feel I am in good company with Morihiro Saito, Morihei Ueshiba, and Koichi Tohei emphasizing these same principles. I discuss and demonstrate this principle using shomenuchi shihonage in this video.