They are also some One-handed Weapons that completely blacks out the shield slot in you inventory, so it becomes impossible to wear a shield
Um no, there aren't. In fact the only way of finding out whether or not a weapon is 1H or 2H is to equip it and see if it blacks out your shield spot.
And I didn't find a shield all that useless. I played a game with my hero slashing with shield and my DK slashing 2H, and I found my hero the better of the two. Naturally, it depends a great deal on the weapons you find (the best 1H weapon I found was actually better than the best 2H weapon I found), but still, being able to block about 80% of the attacks isn't bad... (although I believe blocking was nerfed since then). I just had all of the enemies attack my shield guy, so the other could just take a swing at them without any personal danger.
