Virtues of a Sharp Knife
A sharp knife works better
Sharp knives cut with less brute force than dull knives. Less brute force does less damage to the food, which you can easily see by looking closely at the cut. Delicate ingredients, like herbs, sliced through cleanly will look fresher for longer, whereas a dull knife will crush more of the cells surrounding the cut, which ultimately accelerates wilting and discoloration.
But more than this, a dull knife slows you down, while a sharp knife makes prep easier and more enjoyable.
A sharp knife is safer
A sharp blade is predictable. When it strikes, or is drawn across the food’s surface, it won’t slip. This makes it easy to control how the blade moves through the food, giving you control over your chopping or slicing. A dull blade will slip, which makes control difficult and risks slipping off the food and plunging into your fingers. With a dull knife, it’s only a matter of time until you badly cut yourself.