I'm not convinced on the "worn around the neck" part. A tool might be perforated to hang from the belt, from a peg board, from some other tool rack, for carrying on a pack, or for a number of other reasons. You don't want an essential tool where it might be lost or stepped on, so you're more likely to take the time to create a secure way of storing/carrying it. "Pendant" sounds like an ornament, but I don't think of my tin snips as ornamental, nor would I wear a soldering iron as jewelery on a thong.