Hey guys, I confirm the bug, as i encountered exactly the same bug, during the Temle of Eorath exploration, Concelhaut Parasitic Quarterstaff replaced my Weapon Set 1 and cant remove it from there, plus my grimoire disappeared as well, thus completely making my Wizard uplayable.
Here is the link with my save as well:
http://speedy.sh/YvwZj/0e0c83aa93924c4ebbc4c324fffbdcd6-8277136-GildedVale.savegame
I would appreciate if you could fix it for me as well. So far i enjoy wizard class run and would rather not to restart the game as im already 6 hours into the gameplay.
Thanks in advance.