Recently purchased a used Aritsugu A-type to play with. Blade is very odd--the right side looking from the top is very concave outwards although it had been thinned somewhat. The left side is dead flat, as if the knife started life as a single beveled model that has mutated. I can get the edge sharp as hell, but the stiction to the flat side is very strong. I would think the flat side would need to be convexed to help this. I guess I am asking if that sounds right and is there a practical way to do that without power tools?