108 weak points on the human body.
Some of them fatal. Some cause enough pain to incapacitate.
Some just painful enough to numb. The minor ones, daze u for a second or so.
Worst part is, some of these need minimal strength to target and attack. My younger sister could prod a finger into the radial nerves on your thumb and make u scream till u let go. Wait. u let go, then scream. yeah, minor point

On the other end of the spectrum. Just below yer sternum, there's this li'l bit of cartilage called the substernal notch.
Angle a 45 degree uppercut upward right there. a knee will do too. dont really need full force either. accuracy is the key word here.
damn notch dislocates, shoots upward, thru yer ribcage, into yer heart. yer dead before you hit the floor.
freaky? yeah. moral of the story? don't mess wiht someone who knows all this shit.