You don't need a weapon to be heavy to be effective. You just need to know where to put it. I could disable someone with a spoon or a pen. A piece of paper can be a good distraction while you kick or hit something.
The day I got my shodan was interesting. I went to a taikai and was the only person from my training group to go to this one. My teacher's teacher was there, as well as
Jack Hoban. I spent two hours on my 250cc motorcycle to get there, and when I got there, my instructor's teacher came up to me and said, "You're testing for shodan today, right?"
My intelligent response was, "Uh... okay?"
I went through my forms, and was standing watching some other people who were testing when I heard a yell from behind me. To this day I'm not sure what I did, but I moved, rolled, and the shinai went full speed down and across, but I didn't get hit. Jack had snuck up behind me and told me I passed as soon as I was back up and facing him.
I was just reading the full site that I linked, and Mark Hodell is mentioned. He was my instructor's teacher.