1. Should we presume the weapon will "fall?" It may not fall. The weapon(s) may be retained with a white-knuckle grip until the actor becomes unresponsive, and then have to be knocked free so the EMS personnel can start their work. He is a sample of one, but a Mr. Montoya held onto his knife, and a snatched SL-20, as I stood and watched him bleed out. EMS were already on-scene, but had to wait until we knocked the weapons from his hands, before they could start any treatment. (It was not my SL-20 that had been snatched; that happened before I arrived.)
2. I stopped firing because Mr. Montoya was no longer a threat. He abruptly changed direction, away from me and the others present, and staggered along for a bit. (Again, of course, a sample of one.) I had never been trained that my handgun was a bullet hose, to be reflexively emptied toward an opponent.
3. I do not understand this moving-of-eyes concept. I saw his left hand, held low against his abdomen, chambered for a thrust, while also seeing his right hand held high, holding the SL-20, ready for a downward forward strike, while also seeing his eyes. Wow, those crazy eyes. I also saw my GP100, including the sights, though not a classic target-shooting sight picture; the front sight and rear notch were in line, but I was looking over the weapon. I saw the instantaneous hole appear. I saw it all. Tunnel vision? No, wide-angle vision. It had to be wide-angle, because we were close; probably just beyond the distance for him to reach my GP100's muzzle with the SL-20*. Of course, I am a sample of one.
4. I certainly did not shoot his weapons, or the hands/arms holding the weapons. Had he been a B-27, well, I would have hit his X-ring. My tactical error was not compensating for his being at a bit of an angle, so the bullet track was X-ring to rear armpit area, but the heart was still within that bullet track, and severely damaged.
For reference, this was June 1993, well before I had attended any type of force-on-force training, as we know it today. I do not claim to be any kind of expert, or any kind of hero, and do not presume that I am necessarily a typical sample.
*I might well have fired sooner, but waited until a colleague, who had been behind the actor, moved safely out of my line of fire. Be aware of what is beyond one's target!