Dolorous Blow

(Spell Compendium, page 70, DnD 3.5)

Transmutation

Level: ; Bard 3; Sorcerer/Wizard 3
Components: V, S
Casting Time: 1 standard action
Range: Touch
Target: Weapon touched
Saving Throw: None
Spell Resistance: No

A longing for battle fills you as you complete this spell. Upon touching the intended weapon, the feeling fades even as a dull red aura encompasses the weapon.

For the duration of the spell, the weapon's threat range is doubled, and its critical threats automatically confirm, so every threat is a critical hit. The latter effect does not apply to any weapon that already has a magical effect related to critical hits.

Multiple effects that increase a weapon's threat range (such as this spell and the Improved Critical feat) don't stack. You can't cast this spell on a natural weapon, such as a claw.