>>511221Traditionally an axe blade has a convex blade for reasons that are difficult to explain. Let's just say a convex blade forces the wood to move unlike normal knife-like blade that forces the wood to deform where the side of the blade touches the wood. Round side slides against, angular side forces itself into, the softer wood. A convex blade is also stronger as the area that is most prone to chipping is thicker and the actual (microscopic) blade angle is wider.
If you don't have any experience with sharpening stuff it's probably best just to follow the bevel. Once the bevel gets too thick, file off some metal to make it thin again.
