In 0.9 the +damage bonus is added on to the base damage of your weapon. Thus, it makes killing Act bosses MUCH easier. Useful for a MF barb, if you sacrifice Chance guards for LoH, you could kill in roughly Meph or Baal in roughly half the time it normally takes a non LoH user. This means your runs are faster which in the long run maximises your chance of getting items. A small sacrifice in MF results in much shorter runs. Also the reason why mace barbs and the IK maul work well in MF runs.