A maul doesn't have to be sharp enough to shave with since the edge is needed only on the first swing. After that, the wedge shape of the head parts the round. A blunt maul will split red oak and other species where you have a crack or check at the ends of your blocks.

Do you have to sharpen a splitting maul?

Conclusion. Sharpening a splitting maul not only makes wood cutting easier, but keeping a sharp maul could expand its lifetime and make it more efficient.

Should a wood splitting axe be sharp?

A splitting axe must not be dull but should be sharp.

The convex shape is necessary for the proper functioning of this type of axe, and it will probably be the limiting factor of how sharp you can get this axe edge.