Subtle Safety

I read about this in a book, and it caught my attention because this summer I will be traveling around New York City on my own and I need to consider safety. I know that 9 times out of 10 the weapons people use to protect themselves end up getting used against them so I will probably not buy any thing like pepper spray. But this does not seem like the kind of thing that could be used against the wearer. It is designed by a jewelry company out in San Fransisco, RedStart Design. They are marketing it more as a way to remember to make safe choices rather than an actual weapon. Would you consider wearing this? I am not sure if I actually like the design or it, but the concept and function is interesting. How to you ensure your safety?