A man with a weapon is the one at a disadvantage. As Bruce Lee put it... The man who pulls a knife on you is at a disadvantage. He will clearly lose the fight. The reason is very simple. Psychologically, he only has one weapon. His thinking is therefore limited to the use of that single weapon. You, on the other hand, are thinking about all your weapons: your hands, elbows, knees, feet, head. You're thinking 360 degrees around him. Maybe you're considering some form of escape, like running. He's only got a lousy knife. Now he might throw it at you. Let him. You still have a chance to avoid it, block it, or he may miss you. You've got all the advantages when you think about it. You just got to keep a level head against someone with a weapon, in my opinion.