Song of Sadness
Aragheim is a legendary hammer, originally wielded by Oradin Brighthammer.
Aragheim, among other things, is able to smash through the barriers that keep souls in the material plane after death, allowing it to send undead and lost souls beyond the grave, quite literally. Notably, it makes destroying a phylactery much easier than it might be otherwise.
From Legend Lore:
Aragheim is said to have been created from a star, falling to the tangible realms when mortals needed its aid against the oncoming darkness.
The Brighthammer smashes the tendrils that hold the dead to this world. It breaks down the walls that protect the wicked, and garners faith with every swing.
The years have seen many battles with the Brighthammer, and all those in the dark plane do fear it. Its wielders have been few. Even those with demigod powers sheer away.
The dragons have coveted the great weapon, keeping it as a prize in hoards unimagined.