The phrase "wast convinced of" is an archaic way of saying "was convinced of." The phonetic transcription for the word "was" is /wʌz/, while "wast" is pronounced /wɑːst/. The addition of the "t" at the end of "wast" is a form of conjugation used in Old English, but is no longer commonly used in modern English. The phrase "was convinced of" means that someone held a strong belief or opinion about something, often after careful consideration or persuasion from others.