On a similar note, on the occasions I've loaned my knife to someone for a task, they've invariably gingerly handed it back afterwards with word to the effect of 'Cor, that's sharp - !'. Er, yes, it's a knife - ! A blunt knife is not a good thing.
When I began in the hotel trade many years ago, I was introduced to 'the tomato test' for grading the sharpness of a knife. Gently hold the 'test knife' at the very end of the handle twixt thumb & forefinger. Draw said knife across a firm tomato and if simply the weight of the knife cuts cleanly into the tomato, it passes - !
Few knives I've come across over the years, including ones owned by professional chefs, would pass.