If the STRONG password policy is set in the my.cnf file, a validate_password_dictionary_file can be specified and you can use your favorite text editor to add the words or phrases you wish to not be valid in that file. Note that words shorter than four characters are ignored. So create a file with a text editor ( mine was placed in /var/lib/mysql/dit) with the banned words, edit the my.cnf file to set the validate_password_policy to STRONG, and also add the path to your dictionary file to validate_password_dictionary_file line of the same file. Restart your server and test.
My test dictionary had words like 'foobar', 'snafu', and 'password' and trying to use password with one of the words in the dictionary file would generate a ERROR 1819 (HY000): Your password does not satisfy the current policy requirement, even if I mixed the case of the various letters in the restricted words.
MySQL 5.7 also added the ability to set lifetimes for password in age, the ability to lock accounts, and stopped adding anonymous accounts (no user name and no password) during installation.
By the way I will be speaking in Detroit at the Converge Conference on MySQL 5.7 security if you would like to know more about this and other MySQL 5.7 related information.