There are several synonyms for the phrase "affix a legal signature." Some common alternatives include "sign a legal document," "execute a contract," "endorse a legal agreement," or "put one's signature on a legally binding paper." All of these options refer to the act of officially signing a document that has legal implications. It is important to note that affixing a legal signature should not be taken lightly, as it often signifies an agreement or commitment that cannot be easily undone. Whether you are signing a lease, business contract, or legal settlement, it is crucial to fully understand the terms and implications before affixing your signature.