Shadow Blade( Tome of Battle: The Book of Nine Swords, p. 32)
In the course of your training in the Shadow Hand discipline. you learn to use your natural agility and speed to augment your attacks with certain weapons.
One Shadow Hand stance,
Gloom Razor (ToB) ,
While you are in a Shadow Hand stance and attack with one of the discipline's preferred weapons, you can add your Dexterity modifier as a bonus on melee damage for attacks made with the weapon.
Shadow Blade can be used in place of Weapon Finesse to qualify for a feat, prestige class, or other special ability. If this substitution allows you to gain a benefit that normally applies to all finesse weapons (those described in the Weapon Finesse feat description), it instead applies only to the Shadow Hand discipline's preferred weapons.