The weightage of the personality test, also known as the interview stage, in the overall UPSC ranking process is significant, accounting for about 275 marks. It complements the written exams and plays a crucial role in determining the final merit list of candidates. The personality test evaluates qualities like leadership, communication skills, and overall personality traits essential for civil services. An effective performance in this stage can substantially influence a candidate's final ranking, making it a vital aspect of the selection process.