The phrase "didst credit to" is a way of saying that someone or something was a positive reflection on a certain person or thing. Synonyms for this expression could include "made proud," "honored," "distinguished," "embellished," or "validated." These words all imply that the action or attribute being credited is noteworthy and praiseworthy. Alternately, words like "discredited," "dishonored," or "shamed" could be used as antonyms for "didst credit to," implying that the action or attribute being referenced reflects poorly on the person or thing it is associated with. Overall, "didst credit to" is a somewhat formal phrase used to convey a sense of respect or admiration, and synonyms for it should retain that sense of gravity and importance.