There are many synonyms for the archaic word "didst on one volition". This phrase means to take independent action or to act of one's own accord. Some common synonyms for this term include acting of one's own volition, self-initiating, independently acting, freely choosing, self-determining, and self-motivated. Other similar phrases to "didst on one volition" might include "acting under one's own steam," "taking the initiative," "doing something on a whim," or "going it alone." Whatever term you use, the idea is always the same: taking autonomous action without hesitation or external influence.