It's called a Grip End Cutter and it does exactly that — cuts the ends off of closed-end handgrips. Many of the aftermarket handgrips that I like are only available with closed ends, but our VFRs, of course, require open ends in order to allow for the weighted bar ends. I stumbled across this simple and effective tool last month and just had to add it to the tool box.
Here I'm about to cut the ends from my favorite grips; Recoil by Biltwell. These grips are barrel shaped, which fit my hands better than typical firm, flat sport bike grips, and they have a soft and grippy feel.
In the past I've simply hacked the ends off with a razor blade as best I could, but a clean cut is virtually impossible.
This is a quick and simple operation. Assemble the appropriate cutter, insert fully to the very bottom of the grip and strike with a BFH on a soft wood surface. Push the tool through the grip to extract the plug.
A great idea, well-executed. This tool opens up a huge variety of handgrip choices. $24 from several eBay vendors.