Trials of Durance
This quest appears in your journal after you accept Durance in the party (M6,1). You do not receive any detailed instructions, because you only need to make sure that Durance remains on the party as an active member.
After you have taken several rests, you will be able to talk to him about the staff. Ask him about it and continue the conversation for as long as possible. At one point, you will learn Durance's entire story. Help him come to terms with the past and point him in the direction he should follow. Completing the quest is only connected with the conversation itself and you do not need to take any additional steps.