My post is about balancing armour available to each class. It is not about the balance of the naked classes, which is a whole separate and very complex issue. We have to assume for simplicity that the classes are balanced. If not, a piece of titan chest armour is clearly not a sensible way to achieve inter-class balance. I have reviewed all exotic armour in the game an compared available stats and abilities between the three classes. Warlocks need a piece of chest armour as good as the titan example I gave.