The word "pacted" is relatively uncommon and may not have many synonyms. However, some possible alternatives include "contracted," "agreed upon," "settled," "covenanted," and "formed a pact." These words all convey a sense of mutual agreement and commitment to a particular course of action or set of principles. Other related phrases might include "entered into a compact" or "engaged in a reciprocal agreement." While the word "pacted" may not be widely recognized, there are plenty of ways to convey the same or similar meanings through slightly different language.