The phrase "were a source of strength" indicates a positive impact. Therefore, its antonyms would imply negativity, weakness, or vulnerability. Some examples of antonyms for this phrase could be: were a hindrance, were a weakness, were a liability, were a burden, were a disadvantage, were a setback, were a stumbling block, were a barrier, were a handicap. Using these antonyms brings a different tone to the sentence and changes its meaning entirely. It's essential to choose the right word to represent the intended idea accurately. Therefore, understanding antonyms for commonly used phrases is a vital aspect of effective communication.