Prior to the Evolution of Combat, all of the croziers were equal to battlestaves in both attack and defensive stats. After the Evolution of Combat, croziers had a magical accuracy higher than even the Mystic staves in addition to the +6 bonus to prayer.
On the update of 24 March2014 Croziers were changed dramatically. The Ancient, Bandos and Armadyl croziers were made 2-handed and had their prayer bonus changed to +6 instead of their old +3. Besides that they were made a typeless weapon which can not be used for combat.
Even though croziers cannot be used to engage in combat with, they can be keepsaked to override all staves.