I investigated a motorcycle accident where the rider hit a mailbox that was mounted on a 3-inch pipe. He hit the pipe on the right side of his neck about 2 inches under his ear. It snapped his vertebrae at the same place it gets snapped if you are hanged. He was killed instantly.
This took a considerable amount of force, 180 pounds (him) moving at about 30 MPH, hitting an immoveable object. A killer needs to know the exact spot to apply pressure and be able to apply counter pressure with sufficient force to snap a joint that is built NOT to be broken.
Cutting the throat is easier, but you have to insure you get the carotid artery. Even then the guy might make enough noise to ruin your day. I think Seals are trained to drive the knife down, They clasp their right hand over the opponent's mouth, then strike with their combat knife over the left shoulder, and driving the knife into the heart. This stops the heart, killing him instantly. Your woman would have to be tall and fairly strong to do this.