Dagger of Falling Ash (3.5e Equipment)
From D&D Wiki
Dagger of Falling Ash: This jagged, smoky +1 dagger emits a trail of hot ash behind its wicked blade whenever it is wielded. The dagger of falling ash deals an additional 1d4 points of fire damage when it hits. Unless the wound is healed by magic or cleaned with a DC 28 Heal check, a hit leaves a permanent horrid black scar. The blade can also be used to light normal fires.
The original Dagger of Falling Ash was created by mixing the ashes of a dead ash rat to the magical mix, though there may be other ways of creating this dagger.
Campaign Notes: Regarded as the signature weapon of the Darkfire Thieves Guild, this nasty little knife is cause enough for most authorities to immediately arrest the owner. The Darkfire Guild members use this to 'write' on their slaves and sacrifices, and to inscribe their guild ranking into their own flesh. This item is given to Darkfire Guild Thieves and Darkfire Guild Wizards as part of their PrC progression.