You can also invest in some good whetstone. These stones can be used in fine, moderate, and coarse grits too. So, using they’ll also be a useful item for sharpening the knives.
However, you will have guidelines on the angle at which the knife has to position in the sharpener to sharpen it; no matter which one you buy.
You can even purchase polishing stones to finish the job appropriately after the knife is sharpened; you can clean it with them.