Mastering rhetoric can significantly improve essay writing for UPSC by enhancing the ability to communicate ideas clearly and persuasively. Strong rhetorical skills allow candidates to construct well-structured arguments, employ appropriate language, and convey messages effectively. Understanding rhetorical devices such as ethos, pathos, and logos can help in engaging the reader while addressing complex topics. Additionally, mastering rhetoric aids in developing a personal style that resonates with examiners. By cultivating these skills, candidates can elevate their writing, making it more compelling and impactful.