Firstly, both of you must go to the Black Arm Gang's hideout Brimhaven. The Black Arm gang member should be wearing full Black armour (Black full helmet, Black platebody, Black platelegs). Then, the Black Arm gang member is to retrieve an ID to enter the building, but you must get two candlesticks from ScarFace Pete first. (Note: You need to give one to your Phoenix gang partner.) Then, you must retrieve a Miscellaneous key, and now your partner can range the level 22 Grip, who drops the key required for the armband. Both of you must bring your candlestick back to your gang leaders for reward, that is: Straven for the Phoenix gang member, and Katrine for the Black Arm gang member.