For multi-stage manual sharpening, we highly recommend the Spyderco 204MF Tri-Angle Sharpmaker System (Est. $60). This sharpener has two sets of triangular rods -- miniature sharpening stones in fine and medium grits -- that fit into its plastic base at preset angles. You hold the knife horizontally, blade edge pointing down, then draw it back across the sharpening rods on first one side, then the other. An included DVD gives more detail on how to do this -- the process is easy and simple once you see a visual example.
The base has several slots set at different angles; changing slots lets you adjust the Spyderco Sharpmaker for kitchen knives with a 15- or 20-degree edge, and users say it excels at sharpening scissors and utility knives too. "There isn't much the Spyderco can't sharpen," writes Scott Gilbertson for Wired.com, explaining that the open design makes it easy to do unusual things like de-burring a Phillips head screwdriver or sharpening wire cutters. You can also use the Spyderco Sharpmaker to sharpen serrated blades.
Overall, users say the Sharpmaker offers reliable, hard-to-beat results with a reasonable learning curve, and they're happy that, unlike traditional flat stones, you don't have to wet or oil the sharpening rods before use. Users warn that you do, however, need to scrub the stones periodically with an abrasive cleanser like Comet or Ajax to remove any lingering particles of steel. They also warn to be careful about not dragging the point of the knife across the stones as this will quickly dull it.
As long as you keep your hand on the base, outside the rods, they do double-duty as safety rails to keep the knife edge away from your hand. It usually takes about 20 passes on each side to sharpen a blade, although you may need to repeat the process with both the medium- and fine-grit sharpening rods.
Our only gripe about this sharpener is the terminology used in its documentation. When the Spyderco manual refers to a 40-degree knife edge, it's actually referencing what most knife-makers and manufacturers or sharpeners would call a 20-degree blade, the standard for Western kitchen knives. The reason for this disconnect is because Spyderco is measuring all the way across the blade, while most others measure just one side of the blade at a time. What Spyderco calls a 30-degree blade would typically be called a 15-degree blade, the standard for Asian kitchen knives, although some Western manufacturers are beginning to use this narrower blade angle as well.
If you want to re-shape the edge on a knife that isn't set to a 15- or 20-degree angle, or restore a more damaged edge, the medium-grit rods that come with the Sharpmaker don't remove enough metal. Users have reported good results, however, with Spyderco's Diamond Triangle Pair (Est. $50), which are diamond rods for the Sharpmaker system. Of course, if a knife edge is severely damaged, you're usually better off sending it out to be re-shaped, but the Spyderco Sharpmaker can handle anything short of that, and is small and light enough to tuck easily in your pocket or a kitchen drawer.
Most users love the easy mechanics of the Spyderco Sharpmaker but, if you're not comfortable with its relatively open mechanics, consider our best-reviewed knife sharpening kit, the Lansky Professional Sharpening System (Est. $45). This system comes with a clamp that secures the knife blade, four grits of hones, from coarse/grinding to ultra-fine, and a triangle-shaped hone for sharpening serrated blades. You attach a guide rod to each hone, then slide the guide rod into a hole on the clamp. Which hole you choose sets the angle for the sharpening: 17, 20, 25 or 30 degrees. Once the guide rod is in place, you swing the hone repeatedly across the edge of the blade at the pre-set angle; anywhere from six to 20 passes with each hone will do the job.
We didn't find much professional feedback on the Lansky professional sharpening system, but users at several review sites say it's pretty easy to figure out (an instructional video helps), and that the coarser hones remove enough metal to work with high-quality hard steel or re-profile a damaged blade.
That said, the Lansky professional sharpening system does have some quirks. A few users point out the lack of a safety guard -- the only thing separating your fingers from the knife blade is your own good judgment -- and blades longer than about 6 inches must be sharpened in sections, so this isn't the best choice if the only thing you're sharpening is long chef's knives. Still, this is one of the most popular all-around sharpening kits because it creates a true razor edge and offers you a lot of control over the finished product, yet feels less intimidating than a full-on sharpening stone; and the wider angles it accommodates come in handy for sharpening utility or survival/outdoors knives.
If you want to skip the learning curve entirely and save some money at the same time, one of the best knife sharpeners we found is also one of the cheapest. The design of the AccuSharp 001 Knife and Tool Sharpener (Est. $10) couldn't be simpler: It's nothing but a plastic handle with a slot containing a tiny, replaceable tungsten carbide sharpening surface. You place the knife to be sharpened on a table, blade up, and position the AccuSharp over the knife blade. Then you apply light pressure as you pull the AccuSharp along the length of the blade.
Whether they were professional testers or home users, reviewers sometimes found it a bit unnerving to pull the AccuSharp over an exposed knife blade with nothing but its plastic guard as protection. Once they got past that, though, they found it produced a sharp edge quickly and easily. Workers in a prominent test kitchen found it especially handy for quick touch-ups, since it's small and light enough to fit in a drawer.
Because the AccuSharp doesn't have multiple sharpening surfaces to choose from, the amount of pressure you apply is the only way of adjusting its abrasion level. In fact, a few users warn that if you apply too much pressure, this little sharpener will take too much metal off and can even nick the knife blade -- so use a light touch. Overall, users love its compact size, price tag and ease of use, and say they feel perfectly safe once they get used to it.
There is some discussion among both experts and owners about whether the AccuSharp really puts a professional edge on knives, but it's so quick and easy to use that in a way that doesn't matter, as long as you keep touching up the blade before it becomes dulled to the point of damage. This little sharpener also lasts a long time; one user says it took eight years to wear hers out.
Reviews indicate that it takes about 20 passes to sharpen a dull blade, be it straight or serrated, with this little device. One note: The AccuSharp is only designed to work with 20-degree blades (the typical measurement for a Western-style kitchen knife) that are beveled on both sides. So it's not the right choice for 15-degree (Asian-style) knives or knives with a chisel edge that is only beveled on one side, which will rule out some serrated blades.