I have two scars on my right hand (from knives) The first was from limbing a small alder pole for a wikiup with a BSA lockback at Scout camp when I was 14 or so. Right index finger at the first knuckle. Blade went straight in, bounced off the bone and came straight out. For a second I though I had escaped harm and then I bent my finger and saw the hole open up. My finger was splinted by the camp medic for two weeks and I resolved that my left hand did not get to hold the knife anymore. The second I got while unpacking my duffel upon arrival at Ft. Hood. I'd duck-taped it for added security against nosy baggage handlers and after cutting through the tape with my spyderco I left it open on the bed while I ripped off the rest. Tape came loose, hand shot down to the bed and found the serrated knife. Right middle finger, sliced off half the skin on my first knuckle. Couldn't find a medic so I walked down to the shopette and bought a first aid kit while holding a paper towel over my hand. That knuckle was numb for ten years before the nerves grew back.
My personal favorite though was a knife I sharpened for a buddy in the army in Germany (I sharpened for anybody in the battalion, $1 and inch, extra for big nicks) It was a little gerber lockback, maybe a two inch blade. I put a shaving edge on it and returned it to him. Two hours later I go down the hall to use the latrine and I find a blood trail leading into the bathroom. Inside I find my buddy and a medic. My buddy had been holding the knife in a stabbing grip while standing in his room with his arms relaxed at his sides. He had turned to answer someone and the knife hand had fetched up against a wall and the now stationary knife encountered his oncoming thigh. It went in to the hilt. First words he said when he saw me looking at him with his bloody leg up on the sink, "Damn [Alocksly] I didn't even feel it go in, that's a good edge". His roomate later confirmed that he hadn't noticed the knife and had walked around the room for a few paces until he said his leg felt "weird" at which time he looked down ad noticed the protruding handle. He denies it but I believe alcohol was involved.