I haven't given it much thought as to the impact weapon use of my Glocks, but I do have a D cell maglight next to my nightstand gun. ASP training back in the day said, never use your flashlight or pistol as an impact weapon. I can buy another Maglight for $35 and the pistols start as over $500 and the light doesn't launch bullets. I am now paranoid about falling on rocks while running.
Thanks for the heads up about Achilles heels. I wish a Glock 20 had a 1911 style grip, or a CZ75 in 40 S&W wasn't so blocky. A crisp S&W single action trigger on every revolver would be nice too.