Sharpening a convex edge can be a real pain in the keister. With a traditional, flat sharpening stone, one must repeatedly and consistently follow the contour of a rounded, convex edge with the flat surface of a stone. Not an easy task.
I suggest that you use a soft, moldable surface to follow the contour of your convex edge. I use amouse pad, but other things like a piece of wetsuit, etc. will work also. For most, lite sharpening, I use compound applied directly to the cloth side of the mouse pad. For more aggressive stock removal (fixing chips, broken tips, etc.) I use a piece of sandpaper on top of the mouse pad.
If you are using oil or water on the sandpaper, be sure to lay the sandpaper on the non-cloth side of your mouse pad so as not to saturate the cloth surface with oil.
I use this method to sharpen all of my convex grinds, like my Fallkniven F1, S1 & A1.