If you choose to carry a fixed-blade knife, rigging that knife on a static line makes a lot of sense from a self-defense perspective. Mike Janich, from Martial Blade Concepts, shows that by looping the line over your belt, you have quick and safe access to your knife with either hand by simply sliding it behind your belt.
When you grab the handle, the knife and sheath deploy together, protecting you from getting cut. The static line then pulls the sheath away from the blade as you complete the draw. This is a very simple and effective way to get and keep your fixed-blade knife at the ready — and it allows you to deploy it quickly.
Pro-Tip: Use Rubber-Backed Tape
Wrap your sheath with rubber-backed tape to help keep it in place behind your belt. This friction layer will help keep the knife stable. You might want to experiment with a loosely fitted belt clip, but the key here is to ensure that the clip comes off your belt every time you draw the knife.