The cast list is actually a pretty good reaction as the instructor was never called by name in the film which is often a good indicator of a character who would be listed as "drunk in the park", "cop #2", "hot dog vendor', or - in this case "Yawara Instructor"
I was curious as well, which is why I went to the credits first and on from there for research.

Um, yes, Artemis - Judd does use the Yawara; she hit her ex in the face with it several times.
Also - how would reading the character names here tell anyone the name of the stick? And if you don't know what it is, looking at the cast list probably isn't the natural first stop to go find the answer.

Are the Yawaras anything like a kubotan? I didn't watch all the movie but I saw someone use something that remindeed me of one. Not sure what it was.

The woman detective does not use, but has instruction on the use of the Japanese wood martial arts weapon called Yawara. You could have known this by reading the character names here at IMDb, and paying attention to the name of the buxom police woman instructor who plays a good supporting star to the principal, too.