In martial systems, weapons are often used as training tools to help coordinate the movement of the body. For your viewing pleasure, me practicing not hitting myself in the head. Oh, and this is really good for opening the shoulders, strengthening and loosening the wrist, as well as all important waist control...plus it looks cool in slow motion,
Slow Movement Builds Coordination
Slow is better...bettermovement.org has a nice article on how slow movement builds better coordination.