Heavy Crossbow +1

Heavy Crossbow +1 is an enchanted weapon. It has a +1 bonus to THACo and damage and the speed factor is one lower when compared to a normal heavy crossbow. With a weight of 12 lbs, it's also 2 lbs lighter. You can't harm enemies immune to normal weapon if you are using non-enchanted bolts, the bolts determine that. This item appears in Baldur's Gate, Baldur's Gate: Enhanced Edition and Baldur's Gate II: Shadows of Amn and it will also appear in Baldur's Gate II: Enhanced Edition.

It's unknown where this item can be gained in Baldur's Gate, as it's not for sale at any store.

It's unknown where this item can be gained in Baldur's Gate II.

In-game description
"A crossbow is a bow mounted crosswise on a wooden or metal shaft, the latter called a tiller. The bow is usually made of ash or yew. The crossbow fires a quarrel (also called a bolt). This crossbow is magical."