I always carry my cross pen on the plane. It would be almost as good as a tactical pen and its very common.
What's a "cross pen"?
I always have mine, and matching mechanical pencil (also a good stabbing weapon), in my shirt pocket. Never have had TSA or anyone else say anything about them in 30+years of flying.
Handy... I'll have to look for one. Thanks :)
My first suggestion would be a good cane (look at Cane Masters or Americane) or a good sturdy umbrella (you won't have to fake a limp). A tactical pen usually looks like a tactical pen I recommend a Cross or similar Ball point or the slightly thicker fountain pen which are really durable and do not look "tactical". A flashlight like a surefire will usually pass security.
Zebra F-301 pen. Stainless steel pen body, cheap ($3), yet good quality. The pocket clips are good and strong too. It won't break. Makes a great stabbing implement.
You can probably get one at any Walmart or Walgreen's (If you can't find it, order directly from the link I provided).
Be sure to get one with a steel body (they also make plastic ones). The #F-301 is one of the steel versions.
Buy yourself a nice knife when you get there. Then either mail it home or pack it in your luggage when you leave.
I know the OP is planning to stay land-locked, but if anyone is flying out and taking a cruise, forget the knives. Not only do you have to pass back through screening when you return to the ship, but you have to pass through the State of Hawaii screening before that. I have cruised in Alaska, the Med and the Caribbean and never had all the security checkpoints to pass through that we had this past April. And every one of them was SLOW. Even Turkey and Egypt were a snap, by comparison.
On the other hand, I carried my monopod for my camera everywhere I went. With the camera off, I used it as a cane/walking stick. Collapsed, it is 22 inches long, weighs 1.5 pounds and has a very heavy pan head on it. Great defense weapon and no one bated an eyelash at it.
enjoy your trip! Kauai is breathtaking...dont forget to travel the "Road to Hana." on Maui and stop and get some shaved ice at this little shack on the side of the road. its on a cliff. you'll know what I'm talking about.