When the person says: "you relax on the way forward", when sharpening a knife, what does he mean?
Here's a video where I heard that term https://youtu.be/0TPDgdo7jfM?t=2m54s
This will generally mean to not apply pressure (press the blade to the stone by either leaning/twisting the edge firmly into the stone, or keeping your fingers close to the edge) while you are in any edge leading phase of the sharpening motion. Edge leading and edge trailing abrasion have slightly different effects (regarding speed, burr formation, fineness of the edge), and so does sharpening at various levels of pressure (highly dependent on the stone used.).