The antonyms for the phrase "more oft-repeated" can be expressed through words such as "rarely mentioned," "infrequently spoken," and "seldom repeated." These words convey a sense of rarity and singularity, contrasting against the abundance and repetition of the original phrase. Other antonyms may include "rarely said," "uncommonly expressed," and "occasionally mentioned." Using antonyms can add depth and variety to writing and speech, allowing for a more nuanced and diverse vocabulary. By opting for words that directly oppose the meaning of "more oft-repeated," speakers and writers can convey a sense of uniqueness and rarity to their audience.