I read recently that your signature tells a lot about who you are as a person. If your signature slants upward, then you are an optimistic person. If it slants downward the opposite is true. If your letters are open and rounded, then you are a warm person, open to other people, if they are closed and tightly spaced, then you are probably controlling and a perfectionist.
What if you use a mark as your signature because you can't write your name? In looking at the signatures and marks of the Berber women of the Argan cooperatives, which I collected and use as the basis for the artwork for Kahina Giving Beauty, I feel that the personalities of these women are truly on display.
Some of the women struggle to create a single letter from their name. Others steer away from letters altogether, and create original pieces of art such as the woman who uses the star in the circle, which is the emblem on the Moroccan flag. Several of the women use a wavy, up and down line, but even though they are the same idea, there are differences in their execution similar to the differences in our handwriting - some are more openly spaced, some tighter together, some slant downwards, some slant upwards.
We tend to take our signatures for granted and whip them out fast, but these women take great care when they put pen to paper to write their names. In a world where most people can't write, I imagine the thought of owning a signature is imbued with great importance and some mystery. The idea of a physical manifestation of who they are, this thing they are called, and which is mostly necessary for legal documentation or pay records is a grand thing indeed.