loco Gold, land of chaos Gold

Obtaining the Silver-light Sword: Once you have all 3 keys, go back to Sir Prysin. Another very small mini-cut scene will happen as he opens the box and gives the Silver-light to you, and which you then brandish about for a bit cheap loco gold.

Hint: If you drop your Silver light and talk to Sir Prysin, he will give you another sword. This way, you could have an extra in case you lose your sword after the quest, instead of having to buy one for 500gp later on.

Killing the Demon - Once you have all your combat equipment and food ready, head to the Stone Circle just south of Varrock.

Once you get within close proximity of the circle, a big cut scene starts. You see three dark wizards and a wizard called Denath.

The Keys: Sir Prysin can be found in a small room on the west side of Varrock Castle (blue circle on the map). He tends to wander out of this room, however, so be warned.

Rewards: You get to keep the Silver light sword - If you ever lose it, you can buy another from Sir Prysin in Varrock Castle for 500gp