I hope there isn't any other purpose for the 50cm long metal shock...
No, for me its two purposes only.
Though I am sure Dr. Morph would manage to find a third use for this big heavy metal torch.
Anyway, back on topic...
If you want self defense then forget martial arts in their traditional form. You wouldn't want to train karate or some style of kung fu for 10 years just to be able to protect yourself. Better go do a year of boxing. You will be much better off in real life situations.
I have seen too many black belts of traditional martial arts get their asses whooped by street kids who never did any martial arts but just tasted lots of actual fights or boxers who actually had some sense of timing and knew how it feels to get hit hard, and how to focus and keep it together after getting hit.
Best way to learn to fight, is to fight, and not kick and punch air over and over. Just saying. Though I do understand that for many, martial arts are not about self defense or fighting. And in that case I would understand it.