Sharp knives are created by people that understand how to sharpen a knife, sometimes you can get a sharp knife by buying some gimmick thing that claims it's the answer to making a sharp knife but you wont get consistent results.
I use a Worksharp Guided Sharpening System and get consistently razor sharp results, and I mean razor sharp. When I shave hair the hairs literally pop off of the skin, you can feel them pop. But I've also gotten results like that from a simple Arkansas Stone, a belt sharpener, and several other sharpening tools.
The secret isn't the tool, it's understanding that there is a simple trick to getting razor sharp edges. The secret is that you need to shave metal off of one side of the blade until the metal rolls to the opposite side and then you switch to the other side and draw the blade across an extremely fine surface until the rolled metal is shaved off, usually no more than one or two strokes of the blade. Of course you also need to ensure that your blade taper is the same on both sides, that the edge is centered on the blade, and that the edge is straight (no nicks or dents).
The tools that claim that they make a perfect edge rely on them having some kind of rest that holds the blade at a consistent angle (or at least they claim it does). Providing a consistent angle is necessary but it's more important to pay attention to the rolled metal. That roll needs to be along the entire length of the edge before you are ready to shave it off from the other side.
