The point of the arbor is to sand the finish flush with it. It won't let you easily sand the finish lower. If you do then you are doing something badly wrong. Proper sanding is an acquired skill crucial to a good looking finish. It takes practice to have confidence.
I don't mean to be so vague when you're wanting specifics, but this is one of those areas where you are best learning under fire. You'll find that the arbors work remarkably well & make it difficult to screw up too badly. There's nothing to be afraid of. If you are worried about ruining a cue, then make a mock-up cue or two for practicing the finish technique. Finish the cue & sand the finish as you normally would, except there's a carbide sleeve at the end to prevent you from sanding past a certain point. I bet if you give it a shot on a mock-up cue or two, you'll find that it makes finishes easier, not more complicated.