One of the things I am forcing myself as a teacher to consider more often of late is footwork. One of our dojo sayings is "Don't fix with your hands what you should fix with your feet." But that requires to teach what or feet are doing and more importantly how. Our traditional garb, the hakama, actually obscures details of our movement, no doubt a tactical consideration in the evolution of the garment. As instructors we need to remove barriers to learning such that our students can not only replace us, but exceed us and elevate the art.
Here's an exercise to play with for the initial movement in response to a shomen attack. In the case we were playing with at the moment of realization, was bokken tori, so consider that distance in the description. Begin in hanmi, assume left for the discussion. The desire is to move slightly offline to the left, avoiding the downward slice of the weapon. Rather than stepping, which disrupts the alignment of the hips and pelvis, we want to slide the forward foot over while doing about an quarter to half tenkan turn. If we slide by telling to forward foot to move, it will have similar effects on balance to stepping. Solution? Lighten the weight on the forward foot, leaving the only contact at the ball of the foot. Now push off with turn back (right) foot, allowing some "stickiness" of the ball of the forward foot to cause drag and therefore turn the foot, allowing the heel to swing out. The heel position dictates the distance the body moves off line. The push from the opposite foot produces a slide that doesn't upset the hips and therefore helping maintain balance and posture. The push also create a spring loading effect that can be used for a forward 3rd foot kote gaeshi.
Try it. Like it, keep it. Hate it, improve it!