RuneScape/Devious Minds

You can start this quest by talking to the Monk near the Zamorak church on the path towards Canifis (east of Varrock) on the Salve River. He will ask you to bring a Mithril 2-Handed Sword to Doric's place, and thin it down so you can string it.

Once you get to Doric's place (north of Falador), you can make a Mithril 2-Handed Sword if you don't already have one, and use it on Doric's Whetstone. It will become a thin-blade, now use a string with it to make a Bow-Sword.

Note: If you can't smith a 2-Handed Sword, you can buy one from the shop in Taverly.

Now head back to the monk and give him the Bow-Sword you made. He will thank you then ask you to do him a little favor. You have to smuggle the orb onto Entrana.

Get your Large Pouch and use it to conceal the orb. Now head to Entrana, and once on the island, go to the altar in the main building, use the concealed orb on the altar. There will be a cutscene of an Assassin killing the monks and stealing the 'relic.'

You need to head back to the Monk from the beginning. Upon finding him you will see that he was killed "by some powerful magic."

Head to Entrana and inform the Head Monk. He will tell you to inform Sir Tiffy Cashien of this. Sir Tiffy can be found in Falador Park.

Once you tell him about what has happened, you're finished with the quest!

Rewards
 * 6,500 Smithing experience and 5,000 Fletching and Runecrafting experience.
 * 1 Quest Point