You get what you pay for and I may yet get one of those proper Pulsar wrenches, but I can "review" another cheap alternative, this adjustable two-prong crab tool:
http://amzn.com/B00JP4L7OKIt works if you're very careful, and I guess you have more control than with one of those side-handled ones. If it's your first time hopefully it's not your watch's first time being a victim: the back of the first case I opened already had a scratch and I added another one. Lessons learned: have a case holder (such as
http://amzn.com/B00NMB19CC or better). Remove the watch band completely to give yourself more clearance. Once you have the tool's prongs in the notches on the screw ring, before doing anything, gently turn the adjustment knob on the tool back and forth to fine tune the width and tightness within the grove you're in. When you start opening, go slow.