For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow –Ecclesiastes 1:18
You don’t go on vacation expecting to kill the guy who suddenly decides to throw your girlfriend off a bridge . . . but you should at least be aware of what you might have to do with your knife*, should it come to that.
Speaking the truth in love, the Dark Arts for Good Guys series continues with The Right To Knife. You owe it to the ones you love to read the whole thing.
Rule #2: Always have a knife.