Drow Halberd

Drow Halberd is an enchanted halberd +3 which turns into adamantine dust when its removed from the Underdark. In inflicts 1d10 +3 points of piercing damage, has -3 THACO bonus, a speed factor of 6 and it weighs 15 lbs. It's dropped by Drow warriors in the underdark area. This item appears in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition.

In-game description
"Drow Halberd +3 By far the oldest and most often used pole-arm, the halberd consists of a cleaver-like axe blade mounted on a staff averaging six feet in length. The axe blade is balanced at the rear with a fluke, and surmounted by a sharp spike, usually of quadrangular design. The fluke is sometimes replaced by a hook used to dismount cavalry. A halberd can be best described as a cross between a spear and an axe. This item, like most drow equipment, is created using Adamantine, an alloy of adamantite that quickly turns to dust if removed from the Underdark."