1 shot, for sure and for real, center of mass stop? Never mind the 16 oz limit, what you are asking for is a phaser, a death ray. Nope, it ain't gonna happen, no handgun fills that bill. Handguns aren't long guns, and they aren't death rays.
That said, I carry my PF-9 with confidence, and loaded up it is right about your upper limit on weight. 9mm, properly loaded and placed on target, is good enough to get the job done. You might find that a lightweight alloy small frame .38 Spl revolver would also get the job done and yet still be under your weight limit. Lighter weight options exist in .32 and .380, but then you are in mouse gun territory.
Edited to add...if my life is at stake, why would I quit after one round (unless I were already dead?)
+1. I've got 8 rounds in the PF-9, why would I stop after 1? Just as quick as I could get back on target I'd be pulling the trigger again, until the attacker was stopped or I succumbed myself.