My girl has sweaty hands but I'm not sure since when she started experiencing it. Her hands are not just sweaty but sweat could be dripping from her hands too..
When she was 12 years old, she had to make her identity card. I took her to the department and it was so difficult for the officer to get her thumb print. Her prints were not legible. Finally I had to use my thumb print to acknowledge her almost illegible thumb prints.
She has to use handkerchief very often and it has affected her when she writes. Anyway, she can cope with it and she is still happy..