Ogre Slaying Knife, With a +9 against ogres
Now seriously.
The bones of a virgin aligned in a cross shape form the blade and hand guard template.The silver crosses from each of the 5 main cathedrals of Britain are melted down and used in this weapon. This is then infused with chemiluminescence, essence of garlic and the blood of a priest. The sword is forged in the fires of a sacrificial funeral pyre, over the body of a king. Now the blade has been forged, it must be honed.
The honing of said blade is too delicate to leave to such tools as whetstones, the very air must shape it. For 3,000 years, a blacksmithing family swing the sword in the air, letting the air form is shape and sharpness. After these years have passed, the ultimate weapon has been created. Fusing elements of Death, Sacrifice, Chastity, Blasphemy, Dedication, Loyalty, Perseverence and Hope. The the blade is named, Sonis.