Spoiler Alert, click show to read: 
Flail of Ages +5 (BLUN30)
Location(s)
[ToB] Abyssal Fortress - Forged for you by Cespenar the Imp for Flail of Ages +4, the Electric Flail Head, and 5,000 GP


Mace of Disruption +2 (BLUN25)
Location(s)
Docks District (Cromwell's House) - Forged for you by Cromwell the Dwarf for the Mace of Disruption +1, Illithium Ore, and 7500 gp

http://www.gamebanshee.com/baldursgateii/weapons.php