Hi Blondelle--The Body Blade can be a good adjunct for a fitness program, but I wouldn't expect any startling results from it. It probably wouldn't increase strength much in a person who wasn't rehabbing an injury and/or very deconditioned, although the light weight, short range of motion and momentum assist make it a safe choice in physical therapy.
Since we're always trying to improve function (strength) as well as appearance, it wouldn't be my first choice for upper body work. However, if you enjoy using it and are seeing results, stick with it.
I actually had one some time ago, but sold it because it was only challenging for a short time. Once you reach a plateau with it, there are no strength gains to be made.
It's also important to note that seeing increased definition (tone) in any body part might also require a generalized decrease in body fat. The Body Blade would not be the best choice for this either.
BTW, the Shake Weight should not be taken seriously. No one should believe that the people in the commercials look that way from using it.
American College of Sports Medicine Certified Personal Trainer