I've already finished the game in normal mode and am curently playing the HoF mode. I've brought back the sword to the ghost and he's shown me where he's thrown the root to. The problem is that I haven't been to the wyvern room before that. So, when I went there I killed the wyvern and 2 more guys but no root, and yes I've rested a cuple of times but nothing. Just thought to warn you of a possible bug in the game or if it's not to give you something else to laugh to. :)