Currently there isn't a way to have different password policies in the UI. You could possibly setup remote authentication and then use the AD/LDAP server to control password complexity. You will then map the user to the role in the UI. If you have APM you can use APM for GUI auth and then you can possibly do the same thing.
If you would like to see this feature added you can always open an RFE request with F5 support to consider adding to the product.