When it comes to synonyms for "signed by one of two factions," there are a few different options to choose from. One possible choice is "factional," which can be used to describe something that is related to or affected by factions or internal divisions within a group or organization. Another option is "partisan," which can be used to describe something that is characterized by a strong, often biased support for one particular faction or party. Alternatively, you might use the word "divisive" to describe something that has created divisions or conflicts within a group or organization. Ultimately, the best synonym will depend on the specific context in which the term is being used.