What is the theme in Siege of Darkness by R.A. Salvatore?

Characters in the novel, Catti-Brie in particular, are both figuratively and literally called upon to face their demons. Catti-Brie's demons include her enchanted sword as well as Berkthgar and the memory of her dead fiancé. Catti-Brie's sword wants to be carried by the best warrior alive. The sword considers this warrior to be Drizzt. When unable to convince Catti-Brie to kill Drizzt, the sword possesses Catti-Brie in an attempt to make Drizzt understand its desires. Catti-Brie spends several days alone with her sword, conquering its strong will. In the end, she is victorious over her sword.