You can use the knight’s shield for things other than blocking in Trine 2. Frozenbyte released a short video of some of its other applications today:
The knight also has a new Hammer Throw skill in Trine 2. Frozenbyte are trying to give both the knight and wizard more uses in the game, so players aren’t discouraged from playing as them this time around, and simply sticking with the thief.
Something else Frozenbyte recently mentioned on their forums is that you can combine online and local co-op play in Trine 2. The game supports up to three players in co-op, so two players will be able to play on the same machine, with a third one joining them over the Internet.