You can get numbness from breathing heavily and the amount of adrenaline your body pumps out in a fight makes it so you aren't feeling pain the same. Weed wouldn't help you in a fight it makes your reaction time slower and isn't stopping you from getting knocked out.
Weed doesn't make you eat anything that is like saying alcohol makes you take a spin in your car. You may want to do basic instinctual acts more on both because your inhibitions are lowered but they don't make you do anything. If you can't control yourself on drugs you can't control yourself off of them. I can get destroyed on weed and alcohol and hold a cogent complex conversation and refrain from doing anything stupid your actions are a you problem not a weed problem.
Weed can give you numbness if you have no tolerance for it and smoke something strong but it isn't anymore dangerous than being drunk and really compared to something like synthetic opiates it is laughable.