TML said:

How was he merciless and powerful? All he did was look cool and did some gymnastics?

It's been a long time since I saw the film, but from what I can remember, I agree with TML. The character seemed largely a creation for toy merchandising & Halloween costume sales. He was little more than a posed figure. Other than his twirling, he did very little.

Which gets back to Zombie's point earlier in the week of how Boba Fett was also just a posed figure, yet Lucas squeezed uber-mileage out of him.

As has been the case with Lucas since the early 80s; he doesn't need writers or actors. He just needs a design group and a marketing department.