An ornate longsword that is easy to use but also reminds the wielder of its use.
Demon hide Whips that will punish the wielder for injustices.
A magical one and a half handed longsword once wielded by an innocent child forced into the horrors of combat.
UPDATE: Fixed a few flaws to balance the weapon some more and filled a plot hole.
UPDATE: Decided to change the end of the story to have a more fitting reward for a war hero. But the tale still takes a tragic turn.
The PCs encounter an elaborate trap room, designed to fill with water, drowning those inside. Clever and resourceful, they disable the trap and move on.
Only later do they discover that this room is part of the elaborate cooling system that prevents beasts of elemental fire from overrunning the complex. While the fiery beasts run rampant, they begin setting fires, which causes the complex to become increasingly hot and smoke-filled. Additionally, the PCs now have to fight their way out past aggressive fire creatures...