Purifier

Purifier +4 is an enchanted bastard sword which can only be used by Paladins. It deals 2d4 +4 points of damage with +4 additional points of damage against chaotic evil aligned creatures, has a -4 THACo bonus, weighs 6 lbs and it has a speed factor of 4. Also, the weapon gives the wielder 20% magical resistance. This item appears in Baldur's Gate II: Throne of Bhaal and Baldur's Gate II: Enhanced Edition.

It can be upgraded by Cespenar, which requires the Eye of Tyr and some gold. The weapon can be found on the third floor in the maze of the Watcher's Keep. In one level of the mage, there is rock in the center of the area, which can be interacted with. If an evil aligned character interacts with, the rock will cast some spell which damages the evil character (Holy Smite?). If a good aligned character interacts with the rock, they will gain this bastard sword.

In-game description before upgrading
"This single handed weapon is infused with the very essence of virtue, and is rumored to be the sanctified blade of the famous paladin Sir Wediyer. The weapon was lost when Sir Wediyer pursued a fleeing pit fiend through a planar rift. Neither the fiend nor Sir Wediyer ever returned."

Upgraded
Purifier +5 now deals 2d4 +5 points of damage with +5 additional points of damage against chaotic evil aligned creatures, has a -5 THACo bonus, weighs 5 lbs and it has a speed factor of 3. Also, the weapon gives the wielder 30% magical resistance and it can be used twice per day to cast Dispel Magic and once per day to cast Mass Cure. This weapon is now a very powerful weapon, perhaps the most powerful of it's type or it could be Foebane.

In-game description after upgrading
"With the Eye of Tyr set into its pommel, Purifier is perhaps the greatest single instrument of holy justice on the face of Faerun."

Legend
& = before the upgrade.

! = after the upgrade.