Yep.I'm good enough with a gun but I would like to learn how to kill somebody with my knee, you know any good tricks?
When someone attacks you by running at you, pivot to your strong side, trip them with your strong leg. As they fall forward, grab the back of their head and guide their throat toward your weak knee, which should be bent as you go down with your target.
That will destroy their windpipe.
Just make sure your actions justify deadly force.