Blade of Athabasca:

The wielder gains +1 Prowess. Once per session, at the start of a session, the wielder may designate one character or unit as their Rival. All rolls to attack, defend, or to duel roll twice and take the higher of the two; and all attacks made as a ruler unit against the Rival ignore all armor. If the Rival is not destroyed by the wielder personally, or does not lose at least 1 Health State directly due to the wielder, the wielder becomes Bedridden. If the wielder is already Bedridden, they die.