Mace +3

Mace +3 is an enchanted weapon. When it's compared to a normal mace, the weapon deals +3 points more damage, has -3 THACo bonus, a speed factor 3 points lower and it weighs 2 lbs less. This item appears in Baldur's Gate II: Throne of Bhaal and Baldur's Gate II: Enhanced Edition.

It can be bought from the Tankard Tree and Karthis al-Hezzar.

In-game description
"The mace is a direct descendant of the basic club, being nothing more than a wooden shaft with an iron head mounted on the end. In this case, the head is pyramidal and seems to glow with an inner blue light, as it sits atop a polished oak shaft."