imo, a 60 card arena deck should only have 5 braveries max. Never 6 because of double draw. Laying bravery when you have double draw gives your opponent more of an advantage then you do. With bravery, we will assume you and your opponent can draw 2. When you use bravery and have double draw, you each gain 2 plus 2 that you had from your turn. Your opponent gains 2 from bravery plus 1 from his turn, making it a 4:3 ratio. Normally you would draw 2 and your opponent would draw 1, making it a 2:1 ratio. The 4:3 ratio favors your opponent more then the 2:1 ratio and thus bravery helps your opponent more then you do in arena. However, this might not be true depending on what cards are drawn. Thus bravery is only rather useful in arena decks with double draw if its a combo deck or deck out deck. Otherwise, more likely than not, you'll have helped your opponent out more then yourself.