Varun's main weakness in the interview was his inability to provide coherent and relevant answers to the questions asked. This could be due to nervousness, lack of preparation, or misunderstanding the interview format. His responses were often one-word or completely unrelated, which prevented any meaningful assessment of his skills and fit for the role. Varun needs to focus on improving his communication skills, specifically his ability to understand and respond to interview questions effectively. Practicing mock interviews and receiving feedback could be beneficial.