Darklight

Darklight is a magic sword created from the sword Silverlight during the Shadow of the Storm quest. In that quest, Silverlight is transformed into Darklight after being dyed with black mushroom ink and then being used to destroy the demon Agrith-Naar, which coats it in ichor. Both Silverlight and Darklight can be mounted on the wall of a Quest Hall in a player's home. This weapon cannot be made using the Smithing skill. When using Darklight agains demons, it increases damage by 60%; however, its accuracy remains the same as that of Silverlight. Darklight is also used to remove the fire shield from around tormented demons, which significantly reduces their Defence. It can also be used to kill vampyres.

Darklight has a special attack, "Weaken", which uses 50% of special attack bar and lowers the opponent's Strength, Attack and Defence levels by 5%(twice agains demons) on a successful hit.

Retrieval
If a player loses Darklight, it can be retrieved by talking to Sir Prysin in Varrock Castle and paying him 1,000 coins. Multiple Darklights can be obtained by using the Drop trick, but if a player is on a free-to-play world as a member, Sir Prysin will say he cannot trade with the player because Darklight is a members only item.

If a player loses their Darklight but have a Silverlight in their possession they will not be able to buy Darklight back from Sir Prysin. They must drop the Silverlight and then go back to Sir Prysin in which turn will allow them to purchase a new Darklight for 1,000 coins.

Trivia

 * Oddly enough, the Varrock Museum display plaque calls Silverlight, and therefore Darklight as well, a sword made of steel. This is odd since both Darklight and Silverlight may be used to slay Vampyres, who can normally only be damaged by weapons made of silver. This discrepancy can be explained by the ‘magical treatment’ alluded to by the Varrock museum's display and by the God letters, where Guthix claims responsibility for the creation of Silverlight to restore balance following the appearance of Delrith.
 * On the 15 December 2009, Silverlight received a graphical update. However, black Silverlight and Darklight did not although the mounted Darklight in a quest hall did receive a graphical update.
 * On the 21 December 2009, Darklight received a graphical update.
 * When it was updated, many players had not realised and mistook it for a new 'dragon sword' because of its reddish appearance.
 * Darklight was updated in the same system update that released the 2009 Christmas Event.
 * Darklight is held forward, i.e. not pointing up, but Silverlight points upwards.
 * Before the graphical update, Darklight used to look like the black ink-dyed Silverlight in terms of colour. Now, Darklight has a slightly redder tinge compared to the dyed Silverlight, which actually has a black blade.
 * Additionally, Darklight's special attack somewhat resembles the Armadyl godsword's special attack.
 * If Darklight is used on Sir Prysin, he will believe a key is given to him (like in the Demon Slayer quest).
 * Once you get a Darklight and you run out of days on your membership, you will not be able to get the Silverlight (this appears to only affect some players).