The angle on the flat side is between 23 and 24 degrees. To sharpen, use a trailing motion with the ceramic rod on the flat side, drawing the knife from the base of the blade up to the tip. For the convex side, use a strop (leather, often impregnated with a polishing compound). The angle of the convex side is irrelevant as the strop will take the shape regardless. If you find all that to be a pain, grind off the the convex edge and sharpen it as per usual.