The term 'branding tool' can be summarized by the crossword solution 'IRON, ' which is a four-letter word. IRON is a metal that has been used for centuries to create tools and weapons. In modern times, it is also used as a branding tool, where it is heated up and used to burn a design or logo onto an object. This is a popular technique used in branding, as it creates a permanent mark that is difficult to remove.