step 1. acquire the glory kill range rune
step 2. replay the first mission and glory kill every demon in sight. this should be enough to upgrade it
step 3. when you need to escape, find the nearest possessed or unwilling, and blast them with the pistol until they are staggered
step 4. lead the strongest enemy as far away from your target as possible
step 5. press F while still in range, and once the animation is finished, strike your target from behind
this works best when fighting a mancubus, pinkie, cacodemon, or hell knight