*scratches head*
You did not actually do anything extraordinary? Maybe you have some misconceptions about the entire Armory system?
All that you did was put up Protect and Stoneskin and then change to Gladiator again. Of note was that you did not even equip your Protect and Stoneskin on your Gladiator directly, which you could. You ARE aware that for every 5 levels in a particular class you can equip one cross-class ability, right?