Intro: Hidden Blade
First you need to make a shape like the one below except maybe less pointy. This will be the base
now tape a strip of paper to the non pointy side of the base. This will hold it to your arm.
Now take two chopsticks and tape about 2 inches of the chopsticks to the point end of the base.
Now make a paper loop secured with tape now take a small strip of paper and wrap it around the two chopsticks and the part of the strip in between the chopsticks tape that part together and your done.
Now put your arm through the big loop and your middle finger in the smaller. To use them whip your hand out and they will whip out.
Below is the finished product.