In the below video of this rather harmless Dindu warrior being felled by yet another sly Asian, one gets to see not a back fist, which is a martial arts, bull shit slap with the back of the knuckles, but a spinning backfist, a KO blow in kickboxing, which may also be used in stick-fighting and without spinning. In this case the base of the back of the fist, just above the wrist landed, which is better than the knuckle landing and not as heavy as the edge of the hand landing. The pivot action was nice, as was his footwork in general.

The knuckles hitting on a backfist make a "konk" sound

The back of the fist makes this slapping sound

The edge of the fist makes a thudding sound

The wrist makes a cracking sound

The edge of the flexed outside of the forearm makes a crunching sound

This Dindu was basically hit with a level 2 shot on a scale of five.

In bare knuckle boxing this was called the “chopper” or the “pivot punch.”As you can see, when it lands it is a very effective punch.

While we are on the subject, the elbow to hand motion, utilizing the tricep, is the same as that used to ice pick with the knife or dagger. In 2011 Charles severely concussed me with a spinning hammer fist with the butt of this stick, which caved in my fencing mask and made my legs do the noodle walk. Although I did not go down, I was stupid and slurring my words for a week.

When fighting fools and not overused, this is an excellent weapon that is safe for the hand and accesses the thin side of the skull. The spin is not necessary. Try this.

Throw a right hook at the bag and miss. Now bring the bottom edge of your fist back in a back-handed hammering blow and pivot off your rear [left] foot. This is not a KO blow against a seasoned fighter, but gets in. I scored with this against my fighters easily even as a limped around fat and slow in front of them. The added beauty of the backfist is that if the forearm strikes it is still an effective blow.

If you are considering reverse grip knife fighting, practice hammering blows on the bag, being careful not to hit too hard with forehand shots and to stop short of full elbow extension. Do this without a knife in your hand, or a blunt. When you stab someone the blade is going to go through them like they’re cheese and all you are going to feel is your fist hitting the surface that the knife punctured.