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Moran
edge 
Concave
edge
The Moran Edge
The currently hot blade grind among custom knife makers is the Moran Edge. This is named after Bill Moran, who popularized it on his now classic knives . Bill calls it an apple seed shape. This is a slightly convex profile, extending to the back of the blade edge, with the radius of curvature becoming more acute toward the edge. This seemingly gives the best possible edge. The slightly wider angle at the edge gives the effect of a micro bevel. The smooth transition to the nearly parallel sides of the blade causes minimal resistance moving through the medium being cut. The edge can be made very keen, but is still durable.
The only disadvantage to this profile is the resharpening. You really need a slack belt sander to maintain the edge. (Bill Moran can do it without one, but most people use a grinder or sander to form and maintain this type of blade.) Successive conventional resharpenings without a slack belt will result in a progressively blunter edge. If you're the type who uses a prize sword, knife or axe and want the best possible edge, this is the best choice.
This is an old axe that was restored using a Belt Lift™. The convex edge is obvious. We used an axe for demonstration because the large edge area clearly shows the curvature. Final polish was done with a leather belt. We recommend using only the leather belt method for fine blades. Coarse grinding of blades is best used in initial shaping or drastic repair situations.
Below is a large maul that was reground in about 20 minutes! This was done on a Delta 4" X 36" belt sander with a Belt Lift™. The grind was not taken to the leather polished level of the axe above.