As someone who was “cut” in the line of duty, until you are faced with it you will never know how fast it happens. Anyone within 21 feet or so of you with a knife can close that distance and cut you before you can draw your baton, taser, pepper spray, or weapon. In that circumstance you draw the weapon that will provide the most efficient stopping power and allow a better chance of survival after initial contact if they cross the distance and make first contact. Even then from within 21 feet they might still get you before they go down.
there was no knife that I saw and certainly no threat