^(?=.{2,8}$)(?=.*?[A-Za-z0-9])(?=.*?[\W_])[\w\W]+
This regular expression allowes 2 to 8 character passwords. It requires to have at least 1 alphanumeric (letter/number) character and 1 non-alphanumeric character. You can test it here.
If you want to change the minimum characters required or higher the maximum. Just change the 2 or 8.
