Your assessment is spot on. We teach the same techniques for the kuboton using common items, ink pens, pocket flashlights, etc., in the dojo. Most anything can be used as a weapon in the right hands. It all goes back to training.
Just remember, don't bring a knife (or a kuboton) to a gun fight. Train all levels of defense, so that you can respond with the appropriate level of force.
The best thing about having one on my keychain is it's harder for me to lose my keys