Crippling Stab (3.5e Feat)
From D&D Wiki
Crippling Stab [General], [Fighter], [Stealth]
Quickly stab an enemy to get them to break their concentration.
Prerequisite: Slight of Hand +4, BAB +6, Light Weapon Proficiency, A weapon that deals Piercing or Slashing Damage.
Benefit: When you are being held in a Grapple, if you have a Light Weapon such as a Dagger, you may make a Slight of Hand Check. This Check is opposed by the usual Spot Check. If your opponent succeeds this Check, they are entitled a Reflex Save DC 12 + Slight of Hand Skill. If they succeed, they immediately disarm you while keeping you Grappled. However, if they fail their Reflex Save, or if they fail their Spot Check initially, you reach back and stab them dealing normal damage. Your opponent is considered Flat-Footed for the purposes of them losing their Dexterity Bonus as they hold you in the Grapple. You may make a single strike at your highest BAB, while all other strikes suffer a -2 penalty; A Fighter with a BAB of +11/+6/+1 may attempt up to three strikes at a BAB of +11/+4 (6-2)/ -1 (1-2). When you strike your enemy, they must make a Fortitude Save DC 10 + Damage Dealt. If they fail this DC, you are automatically released from the Grapple.
Normal: You must break your opponent's opposed Strength Check to be released from a Grapple.
Special: You may instead use Armor Spikes if you have them for this Feat, but only if you have Weapon Focus [Armor Spikes]. Additionally if you have Combat Reflexes you may make an Attack of Opportunity against your opponent when you become released from their grab. Feats such as Rapid Thrust or Flurry of Blades that allow you an additional strike at your highest BAB, or Two-Weapon Fighting, allow you to make the additional strike, however as listed above all following strikes after the first suffer a -2 penalty; A Fighter with Rapid Thrust and a BAB of +11/+6/+1 may strike up to 4 times for +9 (11-2)/+7 (11-2-2)/+2 (6-2-2)/ -5 (1-2-2). The values include both the the -2 from this Feat (All after initial strike) as well as the -2 from Rapid Thrust (All strikes in general).