Hammer Of Thunderbolts

This +3 Large returning warhammer deals 2d6 points of damage on a successful hit. In the hands of a wielder who wears a belt of giant strength and knows the weapon is a hammer of thunderbolts (not just the +3 warhammer it appears to be), it becomes a +5 Large giant-bane returning thundering warhammer with the following two properties. One, when the bearer hits with the hammer as a thrown attack, it emits a powerful clap of thunder, causing all creatures within 90 feet to be stunned for 1 round (DC 15 Fortitude negates); the wielder is not immune to this effect. Two, the hammer's range increment increases to 30 feet.

A hammer of thunderbolts is destroyed if heated in a fire giant's forge and quenched in the blood of a good-aligned humanoid, which causes the iron of the hammer to become so brittle it shatters the next time it is used to strike. Only bathing it in a fire giant's blood can reverse its brittleness; once shattered, nothing can do so.