I've heard the phrase "use only the weight of the blade" to describe using very light strokes. I never heard any instruction on exactly how to do this. One day it came to me how to accomplish this seemingly easy task. What I'm about to say works on smaller knife (pocket knives, paring, etc.). To keep only the weight of the blade on a stone or strop you want to control that by having only the weight of the handle on your fingers as they wrap around the handle. Forget about edge angle for a sec. If the handle is resting on one or two fingers on one side of the balance point of a knife and the blade, being on the other side of the balance point rests on the stone/strop that is a given amount of pressure on the stone. By moving the handle hand closer to or farther from the balance point you can adjust the amoung of pressure the edge is putting on the stone. The farther you move your handle hand towards the end of the handle the greater the pressure there will be on the stone. The balance point issue seems to be the reason this doesn't work well on larger knives. Then again I sharpen a lot more pocket knife size knives than larger kitchen knives so maybe I'm just not used to them. Now about controling the edge angle I just tried using the balance point of a knife to control the pressure on a strop with an 8" chef's knife. Since there was so much blade (weight) below the handle I had a hard time just letting the handle rest on my fingers because the weight of the edge portion of the blade (instead of the spine) made me need to grip the handle tighter to control the angle. So, it seems different knives (size, shape, etc.) will act differently when the handle just rests on your fingers.
I only mention this balance point issue because using a SUPER light touch is a huge key for getting the really sharp, crisp edges. And using the phrase "weight of the blade" may not be the best phrase. The amount of pressure on the stone or strop is really what matters. Not how much a blade weighs. The pressure can be adjusted by moving the handle hand, holding the handle in a different spot, again, no matter how much the blade weighs. Any correction or additional info I'd appreciate because some times in the past when I think I have a good idea or system it proves to somewhat inaccurate if not completely wrong when someone with more experience comes up with something better or a different outlook on a given topic. If I'm wrong by looking at it this way feel free to act like my wife and LET ME HAVE IT!.