What are the rights of a woman's guardian over her? And why is she not considered fully competent?

The Shari'ah has made the guardian (wali) a condition for the validity of a woman's marriage contract. Therefore, it is not permissible for her to conduct her own marriage contract or that of another woman herself, based on the Prophet's (peace be upon him) saying: "There is no marriage without a guardian," and "Any woman who marries without the permission of her guardian, her marriage is invalid." As for her property, a mature, sane, and رشيدة (of sound judgment) woman may dispose of it as she wishes, whether through sale, purchase, or otherwise, and she does not need anyone's permission, except that it is recommended for a married woman to consult her husband. The Malikis, however, differed, giving the husband the right to interdict his wife regarding her property if it exceeds one-third. This distinction between the rulings on marriage and property reflects the wisdom of the Shari'ah in preserving a woman's honor and modesty, as a woman directly conducting her marriage contract might suggest her longing for men. Thus, the Shari'ah entrusted this matter to the guardian, and because a woman may be overcome by her emotions, the matter of her marriage was placed in the hands of her guardian.