First and foremost thieves get scrolls for a reason and they help a whole ton of a lot of they are used correctly. A scion thief has a nightwalker that will take hit for him if he flees returns knifes and circles with parting block you will seal much more kills than a battle thief. Battle berserker thief... sure it works but it isn't going to be your most deadly thief, too many situations where you'll have to be vis or not choose your own battle.