I encountered a bug in the silent library. I killed all of the mobs and searched the bookshelves thoroughly numerous times and the book required to solve the riddle- Teachings of loss: The Nightsinger is nowhere to be found. Apparently this is a known bug because others that have reported the same issue and said the solution is to reload the save and complete the battle in the silent library again. The only problem is I decided to go on without completing the riddle and logged about another 3 or 4 hours of gameplay and many battles before I found that I could not move forward without the spear. I really don't want to go through all that again so I hope somebody here may have another solution.