The Sword of Torm

Demonbane
The sword of Torm was created for him as he rose to deityhood, destroying the demons and devils that reigned over the continent of Arkanna before humanoids appeared. As such, the sword earned the title Demonbane. Torm valued the sword above all his earthly possessions.

Shattering
Torm's greatest test before becoming a full god was imprisoning the minor (but still very, very dangerous!) demon-lord Drallmanaath, the offspring of Orcus. Although Torm succeeded in imprisoning the demon far under Shallowshell, his sword was shattered into five pieces in the process. Four pieces comprised the blade, and the last piece was mostly hilt with a few fragments of blade

Hiding
To prevent followers of Orcus from recovering the blade in order to free Drallmanaath, Torm ordered the blade to be hidden away, with each piece sequestered away on a different plane. This knowledge was kept secret, and only a select few of Torm's followers were aware of where the pieces were. One of these followers, Iorvun the silver dragon that resides near Bellcairn, was given a map and told only to give it to a group of people that he truly believed would go after the sword. As he got older and older, he still hadn't passed the map on. Anxious about the fate of the sword, he was told by one of Torm's servants to just give the map to the next group of adventurers that visited him while on a quest if they weren't total asshats. That just happened to be this party, for better or for worse.

Recovery
With the recent emergence of Drallmanaath near Shallowshell, the sword is in the process of being recovered by the party. They have (this isn't the best analogy) saved 2/5 of the world so far.