Given that the purpose (most of the time) of a weapon is to
induce your opponent to
change their mind about something, it is not always necessary (or even desirable) to have a weapon that you actually expect to use (see
Nuclear Deterrence). With this in mind, there are even more entertaining possibilities here!
Ideally, a weapon is even more impressive if it requires skill to wield, and the wielder has produced a convincing display (or front) that they in fact possess said skill. Martial arts are a prime example, particularly those which require quickness and precision over sheer muscle power. Bruce Lee with nunchaku would never make anyone believe he was *stronger* than, say, Andre the Giant at his prime; however, he would damn well come across as more lethal.
So, what can we do with duct tape that would, when mixed with precision and speed, produce the promise of (adopts Saruman voice) PAIN! Hm. Well. Ever managed to get duct tape stuck firmly to your epidermis, especially if you have *any* body hair whatsoever? Right. Ouch. Worse yet, ever managed to get it stuck firmly across a really sensitive spot like, say, a nipple? Sure, it's not a problem to have it stuck there. It's the jerking it off (heh) that's the problem.
So: Picture yourself in a dark alley, one day, just minding your skulking-in-a-dark-alley-business. Suddenly, from around the corner, there steps a figure in a costume not unmindful of The Blue Rajah, but rather than attack dinnerware, this figure raises its hands to show you its finely-machined, form-fitting, wrist-mounted...
duct tape dispensers.
Then, just picture the horror, as said figure smoothly leaps into an intricate dance of martial power and clarity, during which you feel the light and feathery touch of its hands across your lips, your wrists, the backs of your hands, the back of your neck, and in fact any other exposed skin...
...and when he, she or it has finished, returning to the beginning pose of relaxed readiness, you look down to find that all across your body, squares of duct tape have been firmly affixed to your most sensitive points, complete with handy double-looped dangling ends...
...the easier for your opponent to grasp them by and pull.
and the screams echo throughout the back ways of the city...