The Agiel is the weapon used by the Mord-Sith to torture people. It's power comes from the bond with the Lord Rahl and the Mord-Sith who weilds the torture stick. The weapons cause anyone who is touched by it unimaginable pain, including the person weilding the weapon. Most people cannot even hold an Agiel unless they have been tortured by one.
Mord-Sith are trained at the end of an Agiel when they are young girls, first they are tortured with it, until they break and become only loyal to their "mistress", and finally they have to kill their own loved one (father, mother, lover, friend, etc) with an Agiel. The Agiel is a baton-like stick that has a gold chain around the handle and most Mord-Sith use the same Agiel they are broken with. The Mord-Sith also provide various other responsibilies in the D'Haran kingdom from sexually pleasuring the Lord Rahl to torturing D'Hara's enemies in an attempt to "break them", to turn them loyal to the D'Haran empire. After a torture victim has completed his/her "training" and is completely loyal to their Mord-Sith "mistress", the Mord-Sith "mistress" will announce her successful "training" by wearing a set of more ceremonial white leather robes as opposed to their usual red leather.