Daystar is an enchanted longsword, a +2 weapon in terms of the level of enchantment and it has +2 bonus to THAC0 and damage. However, against evil-aligned enemies it has a bonus of 4 to THAC0 and damage, and in the Baldur's Gate II: Enhanced Edition even counts as enchanted +4, thus being able to work against e.g. demiliches. In both editions it also deals double damage to all undead and allows the wielder to cast the spell Sunray once per day.
This item appears in Baldur's Gate II: Shadows of Amn. It can be found in the secret room of the Crooked Crane Inn in the Athkatla City Gates area. The room is inhabited by a lich, which makes it difficult to obtain the blade early.
|“||Whether created specifically for use in the service of Torm or appropriated at some point in the long history of the church, Paladins of the Loyal Fury have made good use of Daystar in their battles against evil undead. Through magic or blessing it is empowered with the Sunray, a force of pure life energy so potent that it slays both living and unliving.||”|