The hidden bonus of +5 to steal is provided by this dagger. If you go after OSRS gold an opponent with the dagger and 35 thieves are able to steal from them. The seal will be destroyed once you acquire the item and have killed Zamorak and Zamorak, however, if are wearing Azzanadra's Seal, you can get a new seal by contacting an imp if you have lost your dagger.
Lesser Demon invoked will provide black sword shards. Greater Demon invoking will grant the player red sword chunks. K'ril Tutsaroth: Invoking will grant you demonic blade plans and a sword hilt piece. The Demon Butler (it's item name is called Alathazdrar's Seal but the look-up information states it's the demon Butler's) ~ invoking will teleport you to Sergeant Damien. Once you've completed this by invoking it again, it will grant you 200 noted bowls of curry.
Sergeant Damien's invoking will grant you camo gloves and boots as well as dog-tags. These aren't random events, so they can't be put in the closet. Once you've got the parts and plans you've gathered from your seals, you can use them to buy RS gold create the Demonic Blade. You can create the demonic sword using the pieces from the anvil.