So it turns out not only was the wrench not needed, but if it was, I got the wrong kind. All of the watches I’ve dealt with are opened by prying off the backing. This is how I’ve destroyed a number of screw drivers, so I thought a dedicated tool might do a better job. Turns out I was wrong. This wrench is for “jaxa” style watches which have little grooves on the backing which line up with the wrench. The back is then unscrewed.
Whoops. There goes 
6 well spent.
6 well spent.