I would imagine that a very good and sharp fillet knife to the cardioid artery would work. You would have to just have one good solid swipe. I once accidentally (it was opening a gift) stabbed the area between my thumb and forefinger with a very sharp knife that I didn't even feel, that's how sharp it was. I knew I stabbed my self ( there were kids around me watching) and immediately pinched my fingers together. I stood up, watched to the kitchen and told my wife we needed to go to the ER. When she asked why, I opened my fingers and blood squirted out. I honestly didn't even feel any pain and it went in the length of the blade, which was around two inches. Anyways, I think you could make it work, but my question is, how long would it take to pass out in this method?