I always try to do sword class a couple of times a term. My students for the most part seem to enjoy swinging a bokken or wooden sword whether an adult or child there is just something fun about it. Bokken class offers a different kind of focus from regular training. Distances are different and things change when have a weapon in your hands. I love the moving meditation aspect especially when it comes to partner practice.
At the beginning of bokken class I usually play some Kodo drum music and students lay on their back on matts while I give them an imagery story about being a samurai hundreds of years ago. I have several stories I cycle through all designed to see yourself in a warrior state. The kids love this practice, I have actually had a few adults fall asleep lol.
Sword and children can be a challenge, especially if they are excited as they usually are. Safety is priority but they have a good time.