Nunchucks are not deadly nor dangerous, its on the bottom of the hrs law as case notes. I would think because martial arts is a sport/art. So a katana would fall into that until an aggressor uses it in a non-art manner.
Same with a diving knife which is often sharp on both sides. Which is also the definition of a dagger (illegal). Diving knife is g2g.
In many states, if you've had training with "not deadly nor dangerous" weapons like nunchucks, you are required to register in your state of residence at the time you took classes.
This might have changed, because the info I have was from the 80s. A friend of my mom was leaving a concert at the Charlotte Coliseum which is not a very nice area to be in after dark. She stood outside the entrance afterward to talk to friends. Once she started toward her car, she realized almost all the other cars had left. She could see her car, and she could also hear footsteps behind her. She glanced back, and there were two men following her (not another car near hers). She started running, and they in turn started running. When she got to the car, she opened the door and grabbed a pair of nunchucks. She held it up in one hand and yelled, "I'm armed! Don't come any closer!"
One guy said, "That's a gun!" and ran away. The other guy kept walking, then saw she didn't have a gun. She warned him again, and he laughed, "What are you gonna do with that?" When he was close enough to grab her, she flicked the nunchucks, and nailed him between the eyes.
She got in her car (no cell phones yet), and drove to the local police station. The police followed her back to the parking lot, where they found the guy still lying unconscious.
The defense attorney tried to have the charges against the guy dismissed saying she used an illegal deadly weapon. He'd done some investigating, and he didn't find a NC registration for her martial arts training.
The prosecutor then produced a NY State registration -- where she took the classes.
The judge looked at the defendant and said, "Son, you're lucky she didn't kill you!"
So, while the nunchucks themselves are not considered deadly or dangerous, they may be when in the hands of a skilled user. Would be a good exercise to see if Hawaii has any laws regarding martial arts training and such weapons when used by trained individuals.