The phrase "be a source of strength" implies providing support, motivation, and encouragement to others. However, there are several antonyms that depict the opposite of being a source of strength. Some of the antonyms include being a burden, liability, hindrance, weakness, and drawback. Being a burden means adding an extra load on someone's life that they cannot handle. Liability means causing trouble or being responsible for someone's problems. Hindrance means creating obstacles in someone's path. Weakness means being inadequate to provide help to someone. Lastly, a drawback means a disadvantage that prevents someone from achieving their goals. All these antonyms have the opposite meaning to being a source of strength.