 A filleting knife will be thin enough to be very flexible while a carving knife will be thicker and stiffer; a dagger will be thin so it can pierce while a camping knife will be thicker to it can be stronger and more durable.A strongly curved edge, like a talwar will allow the user to draw the edge of the blade against an opponent even while close to the opponent where a straight sword would be more difficult to pull in the same fashion.The curved edge of an axe means that only a small length of the edge will initially strike the tree, concentrating force as does a thinner edge whereas a straight edge could potentially land with the full length of its edge against a flat section of tree.