First of all, that is true love between a husband and wife right there. It cannot be defined in any other way.
And that is the textbook example of staying in the fight as long as you are able to. He knew how to properly use a knife. Probably a livestock slaughterer or have extensive experience in the free range farming and culling world. Arms length distance. Most likely a bear hug and grapple to impede the shooter's limbs so he could not get his gun to bear on time, while the hand with the knife went to work right away. Not stabbing like an amateur, but plunging and immediately scrambling the insides, destroying arteries/veins and dicing organs to shreds. Done right, that mofo's world would have faded to black under 5 seconds. Doesn't matter if he was 3X stronger than the much older homeowner. Once that blade got to work and started ventilating the pressure in his circulatory and possibly CNS, game fucking over.