Belgaer

The "Thinker", Belgaer is a bell that manipulates memory. It can bring back forgotten memories erased from a spirit who has spent too long in Death, or erase memories altogether. If not used carefully, it may splinter the mind of the one who wields it. Necromancers will almost never use the former function, preferring to use the latter for offensive purposes. It can also be used to liberate a bound creature; this occurs in Abhorsen when, after Prince Sameth removes Yrael's collar, Sabriel rebinds him with Belgaer to imbue him with choice and thereby releasing him from servitude to the Abhorsen.