The phrase "old one-two" is typically used to describe a quick and effective punch in boxing. However, when looking for antonyms for this term, one might consider words that convey slowness or weakness rather than speed or power. Some antonyms for "old one-two" could include "slow and steady," "feeble jab," or "half-hearted punch." These terms might describe an ineffective attempt at striking, one that lacks the force and precision of a proper "old one-two." Overall, while "old one-two" may be a specific term related to boxing, its antonyms could encompass a range of ideas related to weakness, slowness, or lack of skill.