Equipping this weapon reduces the max health of the user by 55, lowering their total health to 70. Upon a successful backstab, degenerative effects such as afterburn and bleed end. The victim's total health, including overheal, is then added to the user's own health. This heals any damage taken, and then applies the remainder in the form of an overheal, capping out at a minimum of 75 and a maximum of 210.
The same rules of overheal decay apply to Spy as with other classes. The Spy's maximum overheal as applied by the Medic adds 35 health, which decays in the usual 15 seconds. However, the maximum overheal applied by the Conniver's Kunai is 140, four times as much as 35, so it takes four times longer to decay (60 seconds). The decay rate is approximately equal to 2.33 health per second.
March 10, 2011 Patch (
Shogun Pack)
- The Conniver's Kunai was added to the game.
March 11, 2011 Patch
- Fixed players getting a health bonus based on the weapon they're currently holding instead of the weapon that dealt the killing blow.
March 15, 2011 Patch
- The Conniver's Kunai became tradable.
- All Conniver's Kunais crafted before this patch were upgraded to Vintage quality.
- [Undocumented] The Conniver's Kunai was given a unique crafting recipe.
April 14, 2011 Patch (Hatless Update)
- Spies now can speak their Domination or Revenge lines correctly when using the Knife or Conniver's Kunai.
June 23, 2011 Patch (Über Update)
- [Undocumented] The Conniver's Kunai was added to the crafting blueprint for the Big Earner.
July 12, 2011 [Item schema update]
April 17, 2012 Patch
- Fixed a bug that would cause Medics to reduce the health of heal targets if the target had earned more health than their normally allowed max overheal.
April 18, 2012 Patch
- Fixed health drain happening faster for players with health above the normal overheal amount for their class.
August 27, 2013 Patch
- Fixed a bug that would allow Spies to exploit the Kunai's higher overheal limit.
November 12, 2013 Patch
July 2, 2015 Patch #1 (Gun Mettle Update)
- Changed attributes:
- Health penalty reduced from -65 to -55 (70 Health total).
- Minimum Health gain of 75 on kill.
- Maximum overheal from Kunai increased from 195 to 210.
July 7, 2016 Patch #1 (Meet Your Match Update)
- Fixed disguising with the Conniver's Kunai while spotted by a Sentry Gun causing the Sentry to ignore the Spy.
May 1, 2025 Patch
- Fixed missing lightwarp setting for the Conniver's Kunai and The Half-Zatoichi (community fix from Lindon)