If someone was attacking me, and they were close enough where I could jab them in the ribs, I'd be using that tactical pen for eyeballs, ear canals, creating a shish-ka-Bob with a part of their anatomy, or something else with more proven "stunability". Once they get that close, you have made some pretty severe tactical self defense errors already. Poking them in the ribs at that point would be yet another tactical error IMHO.

Anyway, I'm getting WAY off topic here... Sorry about that.