Two blades are used on hand saws that are operated manually: straight edges and curved blades. If you frequently find yourself cutting areas parallel to the upper half of your body, the best knife to choose for you is straight. The blade with a curved edge is the best option if it looks likely that you will be reaching upwards (or downwards) because it will allow you to apply more pressure to each cut you make since the curved edge will allow you to apply more pressure to each amount.