As you can see here http://pastebin.com/ji9ZTXnD No hammers should be able to be crafted. Yet you can still craft them. Logs to correspond to this issue. http://pastebin.com/GUyy7U2T Not sure if this is on my end or something else.

The allowed and restricted entries are (=should be) equal. They're just both there for visibility.

You can only use one of the two, you can't mix and match. Also Obsidian hammerhead is in both.

The error in the log seems to be caused by a broken material. Either a consequence of the above or another mods fault I'd say.