DIY weapon
Keys come in all shapes and sizes. They can be more rounded, but they can also be pointed. Because just about everyone carries keys when they go out the door, they are easy to use for protection. Holding the keys between your fingers allows you to better attack your attacker without having to be too strong. (Fig 1) As such, there are several articles and videos on the Internet explaining how best to do this.
It is one of many examples of what women do with the idea that they could be attacked at any moment. Or at least feeling that they might. So you see, an ordinary object can suddenly take on a completely different role. Instead of just opening the door or your bike, it can be the literal way that gets you home safely. Have you ever looked at a set of keys this way before?