In retrospect, blocking was overpowered in Diablo II. That a shield gave your character up to a 75% chance to completely erase all incoming physical damage hardly seems fair, and was certainly not realistic. How can a weak Sorceress or Necromancer with a little wooden plate on their arm completely stop the damage from a massive polearm? If the Diablo III system works as Shield Specialization makes it sound, the use of shields should be much more interesting in D3. It would make two-handed weapons more viable, for one thing, since a player wouldn't be giving up 75% damage reduction by using them.