Wüsthof 240/1000/3000-Grit Tri-Stone Sharpener Even if you’re starting with a very dull knife, the three levels of coarseness will whip it into tip-top shape, particularly the slightly softer German steel blades. It comes with a little squeeze bottle, so you can keep the stone properly moistened, and a no-skid base. $50, williams-sonoma.com Shun 1000/6000 Grit Combination Whetstone
The grit on either side of this Japanese-style whetstone is slightly finer than the Wüsthof one, good for the harder (and more brittle) steel of a Japanese knife. This one also comes with a base for safer sharpening.