Me too, I always have my Super Tool with me...made a pouch to hold it and a spare mag for my Kahr. Any sharp tool will shatter a tempered window, even keys held between fingers with a sharp punch (it's gonna hurt your hand, but at that point who cares). Using a multi tool, my guess that, other than the knife blade, the awl or phillips would work. Spring loaded center punches work best, requiring less force/strength to do the job. You can use them under water, something that will be hard to do with a striking type tool, since the water will slow down your blowl.