The 'emergency' in question is generally 'I really do need a gun, but I have no money to speak of'. Still, if you point it away from you, it usually won't kill you.
See here for a list of how to obtain this item, or click to show them.
It can be purchased from Carrow's Steel in the Bazaar and sold to the Bazaar:
||The shop-keeper is tremendously relieved to part with it. He eagerly wraps it in brown paper and string.
||The shop-keeper seems to think you're joking. He turns over the weapon wonderingly over in his hands. Eventually, reluctantly, he pays you.
Effects when equipped in Weapon slot:
See here for a list of pages which require this item, or click to show them.