Above is a very threatening looking device that is actually just an edgy bottle opener ring. It's made by Dustin Wallace, who is perhaps best known for his equally intense Robotagami sculptures available in the Boing Boing Bazaar/Makers Market. The Bottle Opener Ring comes in several sizes and is $49.99. I wouldn't suggest taking it through airport security. Dustin writes:
This ring combines functionality with design enabling you to get some looks while you open your choice of beverage. You are able to wear this ring on the knuckle side or palm side, whichever suits you. It is designed to fit on your ring finger and for you to use your index finger for leverage. If wearing it isn't your style, you can put it on your key chain as well.