Which word refers to one empowered or chosen to judge or decide a disputed issue?

The term that refers to one empowered or chosen to judge or decide a disputed issue is "Arbiter." An arbiter typically has the authority to make a binding decision in a conflict or dispute, often based on an understanding of the relevant facts and legal principles. This role is crucial in various contexts, such as legal settings, mediation, or arbitration proceedings.

In contrast, a moderator facilitates discussions or debates but does not possess the power to make binding decisions. A facilitator helps groups reach conclusions and fosters communication but is similarly not designated as a decision-maker. An advocate promotes a particular cause or argument, representing the interests of others, but does not have authority over disputes between parties. The definition and function of the arbiter clearly align with the role described in the question, making it the correct choice.