Kethavris, the Turned Blade
Kethavris was forged in a city where informants were the true currency of power, a place where every alliance was a transaction and every friendship a liability waiting to be collected. The blade passed through dozens of hands, each wielder leaving their own record of broken oaths in its steel, until the names etched upon it outnumbered the living. It does not corrupt its wielder toward betrayal. It simply notices, and rewards, those who have already chosen that path.
Mechanics
A cursed dagger that records every act of betrayal against allies and channels that accumulated treachery into devastating strikes.
Curse of the Turned Blade
This dagger is cursed, and attuning to it bonds it to the wielder's history of betrayal. The curse is not apparent when the dagger is first held, it feels unnervingly comfortable, almost eager. The curse reveals itself the first time the wielder attacks a creature that is, or recently was, a willing ally (the DM determines when a relationship qualifies). From that moment forward, the wielder cannot willingly unattune from Kethavris without the benefit of a remove curse spell or similar magic. The ongoing effect is this: whenever the wielder deals damage to a creature that trusted them, a former ally, an employer who hired them in good faith, a contact who vouched for them, that creature's name is silently etched into the flat of the blade in a script only the attuned wielder can read. The wielder has disadvantage on Charisma (Persuasion) checks made against any creature who has witnessed them betray someone, as a subtle, instinctive wariness radiates from the blade. The wielder also cannot benefit from the Help action provided by any creature whose name is etched on the blade, the blade severs the thread of cooperation, unable to receive aid from those it has wronged.
Mark of Treachery
Whenever the wielder deals damage to a creature whose name is etched on the blade (a betrayed ally), that attack deals an additional 2d6 psychic damage. This damage represents the blade drinking deeply from the wound of broken trust. This bonus damage applies once per turn.
Compounding Guilt
For each unique name etched on the blade (maximum 5), attack rolls made with Kethavris gain a cumulative +1 bonus, up to a maximum of +5. The blade sharpens itself on betrayal. These names persist permanently and cannot be erased except by destroying the dagger.
The Knife Remembers
Once per day, when the wielder makes an attack roll with Kethavris, they may choose to invoke the memory of a specific betrayal. If at least one name is etched on the blade, the attack roll is made with advantage, and on a hit the target must succeed on a DC 15 Wisdom saving throw or become frightened of the wielder until the end of the target's next turn, as the blade's psychic resonance broadcasts the raw sensation of betrayal directly into the target's mind.
DM Notes
Balance considerations: The Compounding Guilt bonus is the most significant long-term power spike, a rogue who betrays 5 allies effectively wields a +5 dagger for attack rolls, which exceeds Very Rare thresholds if left unchecked. Cap enforcement at 5 names is essential; DMs should track this carefully. Consider whether NPCs count as 'allies' liberally or conservatively to control the pace of accumulation. The 2d6 psychic damage from Mark of Treachery only fires against named betrayed allies, so in most standard combats it will not apply, it is a narrative punishment/reward rather than a constant combat buff. The Knife Remembers is a once-per-day advantage + frighten that is well within Rare parameters. The curse's social penalty (disadvantage on Persuasion for witnessed betrayals) is a meaningful narrative consequence and creates interesting roleplay pressure. This item is intentionally designed to grow more powerful the worse the character's choices become, use it as a DM tool to create consequences and dramatic tension around the betrayal arc. If the character attempts to atone, consider allowing the names to fade with story-appropriate effort rather than mechanical removal.
Generated with: Level 9 · Rogue · Arcane Trickster · Weapon (Dagger) · A theme that fits her character · Mysterious · Rare