"messenger, envoy," late 13c. (in Anglo-Latin); c. 1200 as a surname, from Anglo-French heraud, Old French heraut, hiraut (12c.), from Frankish *hariwald "commander of an army" or a similar Germanic source, from Proto-Germanic *harja "army" (from PIE root *koro- "war;" see harry) + *waldaz "to command, rule" (see wield). The form fits, but the sense evolution is difficult to explain, unless it is in reference to the chief officer of a tournament, who introduced knights and made decisions on rules (which was one of the early senses, often as heraud of armes, though not the earliest in English).
<a href="https://www.etymonline.com/word/heraldic">Etymology of heraldic by etymonline</a>
Harper, D. (n.d.). Etymology of heraldic. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/heraldic