In a self-defense scenario, especially one involving armed attackers, escape should always be the first option you consider. If you can run from danger and survive, you should do so. However, there are often situations when escape is simply not an option. If your back's against the wall, and you have to fight for your life, using an improvised weapon can greatly sway the odds in your favor.
We previously discussed the Millwall brick, a blunt-force weapon made of folded newspaper, as well as carabiner knuckles. While both these tools would be good defense options in a fistfight, they require you to be up close and personal with your attacker(s). If you're facing armed opponents, such as thugs carrying knives or batons, keeping your distance is key to avoiding slices and broken bones. Even a foot or two between you and the attacker can save your life.
Keeping in mind this element of range, consider improvising a weapon from an item you're already carrying: a belt. You can wear a belt almost anywhere, even in locations that might explicitly forbid other weapons, and when swung quickly, it can provide an excellent means of protection. Self-defense instructor Nick Drossos of CodeRedDefense.com shows how to use a belt as an improvised weapon in the video below: