??? Or is it only good for shield? For that matter, does it even go up in skill if you block with a weapon?

Pretty sure it's been confirmed that it does.

Yes... It always has. Well... In Oblivion anyway. All the others, blocking wasn't an active action so it couldn't be done without a shield anyway.

Lots of things that were so in Oblvion are not in Skyrim. Open lock spells and scrolls for example.

P.S. Skyrim is the greatest game ever made.