手中敗笔
[shŏu zhōng bài bĭ]
Directly translated as 'failure in hand', which symbolizes that despite one's efforts, things did not go well, ending up making mistakes that are like botched strokes when painting or writing. This may suggest a negative experience, self-blame, disappointment, failure, regret over one's works, or actions that did not live up to one's expectations.