Have had occasion to spend a lot of time in secured areas where I cannot introduce a firearm.
For those that think they can smuggle one in to a nuclear weapons manufacturing facility, give me a minute to go grab some popcorn- I wanna watch this!
When I could not carry, I always had a non-sparking bung wrench on my keyring. Brass rod, with two 1 inch long brass teeth at a right angle to the rod. Use it to unscrew the bungs of a 55 gal drum. Non-sparking for flammables.
You say it looks just like a kubotan? What's that? Never heard of that. Naw- bung wrench.