The phrase "on one last leg" is often used to describe a person or thing that is in a precarious or weakened state. Some synonyms for this phrase include "at the end of the road," "on its last legs," "on the brink of failure," "on the verge of collapse," "at death's door," "in its final stages," "running out of steam," and "about to give out." All of these phrases communicate a sense of impending doom or failure, highlighting the fragility of the subject in question. When someone or something is "on one last leg," it suggests an urgent need for intervention or help before it's too late.