The authorized signatory of a contract, whether it is a legal person or an authorized person, is usually signed by the legal representative. If the legal representative is unable to sign for some reason, a power of attorney can be issued and signed by the authorized person. The power of attorney has the same legal effect as the signature of the legal representative. First, the meaning of "legal person" and "legal representative" should be distinguished here. Legal person generally refers to institutions or units, such as companies are legal persons; The legal representative generally refers to the main person in charge of an institution or unit, such as the chairman of the company is the legal representative of the company. So the "legal person" mentioned in your question should be the "legal representative of the legal person". Secondly, in addition, it is necessary to distinguish the concepts of "authorized person", "authorized person", "agent" and "principal". In these four words, the meaning of transferee and principal is similar, that is, the person who originally owned the right and is now exercised by others; The meaning of the authorized person is similar to that of an agent, that is, a person who originally had no rights and now accepts the entrustment of others to temporarily exercise their rights; However, the agent and the principal are legal terms, while the authorizer and the authorized person are not. So the "authorizer" you mentioned in your question should be the "agent", that is, the person who accepts the authorization. Third, generally speaking, when signing a contract, the signature of the legal representative or one of the agents has legal effect; If two people sign at the same time, it is also legally binding.
Legal basis:
People's Republic of China (PRC) Civil Code
Article 163 Agency includes entrusted agency and legal agency. An entrusted agent shall exercise the power of agency as entrusted by the principal. A legal agent shall exercise his power of agency in accordance with the provisions of the law.
Article 165 If the power of attorney is in written form, it shall specify the name of the agent, the matters to be represented, the authority and the time limit, and shall be signed or sealed by the principal.
Derivative problem:
Does the company authorization agreement require the signature of the legal representative?
The power of attorney of the company belongs to the general entrustment contract. If the company authorizes someone or an organization to handle the company's affairs on its behalf, it needs the signature of the legal representative and the official seal of the company to take effect. If it is a power of attorney issued by the unit, it needs to be stamped with the official seal and signed by the legal representative to take effect. The official seal of an enterprise can represent the company's behavior. If the company sends a non-legal representative to sign the contract, the other party must provide the power of attorney given by the company to avoid disputes caused by unclear authorization.