I think what people don't understand about feedback is that it's almost impossible to tell someone what they need to know without hurting them in the process. If you can find a way to leave the smallest possible cut, then you may be on to something, at least if you value the process of helping others reach their potential.
I'm not sure if this is necessarily something I learned from using a particular knife, but when
I lost it the point definitely hit home. Sometimes, you don't really remember something until you forget it, just as you don't realize what you have until it's lost.