Silken Glove of the Dark Duelist

Silken Glove of the Dark Duelist
Most recently gifted to Graykar by Gordon of the Borkjä.
While wearing the glove, the duelist gains a +5 to CMB on dueling related activities involving that hand and a +10 to CMD against all dueling activity like disarm attempts when the weapon is held by that hand.
Additionally, any attack made with a one-handed piercing weapon held with the gloved hand has a chance to instantly kill the target provided the following conditions are met:

1. Target must be of equal or less HD to the duelist
2. Target must be humanoid of size Large or smaller
3. Target must not be the main encounter or a character nemesis (named, PC, boss, etc.)
4. The attack must be a successful sneak attack

If those conditions are met, the chance to instantly slay is the wielders dexterity bonus. The victim is reduced to negative hit points equal to twice their constitution score.