The nail file
The Nail File was an object owned by the Legion, or more specifically Jennifer Bloom. It was stolen from her by Joe Miller and used on Martin Ruber but it was later returned to the Legion by Joe Miller, along with the Pen.

The Nail File's power is as follows: If light reflects off the edge of the File and into someone's eyes, they fall into a short but deep sleep. This is obviously useful for Legion members as it can be used as an alternative to shooting them, as it painlessly incapacitates them.