When sharpening your kitchen knives or any other knives it is important to remember three key things. First and foremost electric knife sharpeners utilize spinning discs which can create localized heat along the edge of the blade. This can cause damage to the temper of the steel. This translates to inconsistencies in the hardness of the steel along the cutting edge making the blade susceptible to chipping, premature dulling, and corrosion. By using a manual knife sharpener or sharpening system you can eliminate this possibility. Sharpening systems utilize shoes that are pushed along the edge at a speed that creates very little if any heat, thus protecting the tempering of the steel. The second consideration is creating a consistent bevel along the entire length of the blade. Because electric knife sharpeners require you to drag a knife through the spinning discs, a uniform bevel edge is difficult to achieve. This is due to the difficulty of maintaining consistent speed as the knife passes through the discs. It's also difficult to maintain a consistent angle while pulling the blade. Sharpening systems alleviate this by locking the blade in place and moving the stone across rather than the other way around. Finally the third consideration is that a knife should be sharpened as closely as possible to the factory bevel angle to insure the edge lasts as long as possible. The steel strength and bevel angles are two of the most important characteristics of any knife and should be maintained whenever possible.