I started to go to fencing few weeks ago and got myself a powerball to strengthen my wrist. But even if after you use until you can feel in your arms that you made an effort, I didn't notice many improvements and a complete lack of stiffness. I guess because it forces you to have your arm in a fixed position with a weight, and also having your wrist moving you feel like you are doing a lot of exercise but really you are not doing much.
The other side of a powerball is it use as a toy. Its funny to see how long it takes your friend to make it work and after that compete to see who can make it spin faster.
That made me think that it more a toy that a training tool.
I am right or I am not using it correctly?