In big boards admin will chose 2 or 3 type of moderators with different permissions, actually in most cases.
According to this if you want to give ban access to just one of those groups you cant! cause you have to cut other groups access from warning system. without warning system those groups are nothing, they are just posts wiper.
Its really pain in the neck, it would be great if you add ban permissions for different groups.
P.S: I know who to use warning system and spam cleaner