After just using such a method yesterday for a hose clamp, without the “tensioner”, I have to thank you profusely! I will immediately tell you of my idea to make your tool even better. Because I needed to clamp a 3/16” hose onto a barb I didn’t have a clamp small enough so used some steel safety wire which is very thin. I can see that using your tool would cause me to cut the clamp wire when just wanting to grip it. My idea when building your tool would be to grind the cutting edges of the nippers flat first of all, build the tool and then resharpen the ends of the nippers that aren’t used to grip the wire when tightening.
Either that or use a pair of pliers to build your tool and keep some nippers handy for cutting the wire. I believe that I’ll be using a pair of pliers for mine, but using your idea for the “tensioner”.
Thank you very much!