Brad,
Definitely a thread-restoring file, and a metric one at that.
They are used on external threads.
Very popular with assemblers, especially mechanics. Plumbers usually have one for pipe threads in their box as well.
Typical applications:
1. Cleaning the threads. Often, a previously-assembled bolt will have the threads clogged up with gunk like tape, gasket sealant, etc. Sometimes the fasteners have corrosion (rust) buildup in the threads, too.
Cleaning the threads allows not only easier reassembly, but more importantly, proper torque readings.
2. Restoring buggered threads. Sometimes the threads get mangled from banging into other pieces, or simply from being scooted around on a hard concrete floor (or gravel driveway!).
Provided you still have good thread to overlap, the file can be used to bring the distorted portion of the thread back into proper shape.
If I remember correctly, Blue Point is a somewhat less expensive part of the Snap-On tools line. Should be a very high-quality tool.
Can you use one for jimping, etc.? Wouldn't be the first time a tool was used for a task other than original intentions.
The thread file may get the job done, but an actual checkering file will probably be better for this task, albeit at higher $$.
The checkering file will not only be more precisely made overall, but will have an actual tang, allowing more precision and easier application.
Try it out and see if it works for your application. If it does, great, you saved some money.