The Weaponsmaster is a member of the Phoenix Gang and plays a role during the Shield of Arrav quest. He is located upstairs in the southern alley of Varrock (southwest of Aubury's Rune Shop).
Players who are trying to get into the Black Arm Gang will have to kill him to be able to pick up the two required Phoenix crossbows. He will also attack members of the Black Arm Gang if they try to talk to him.
If a member of the Phoenix Gang tries to take a crossbow, he will notify them that it belongs to Straven and prevent them from taking it. Members of both gangs, or even those not in either gang, can cast Telekinetic Grab once they arrive in the weapon store room to take these crossbows, but may be noticed if they have already spoken to him.