Sonja tricks a sorceress

"This sword," Sonja told her, voice tense with emotion, "was my father's. My father's sword, witch! He forged it himself and used it in combat. When he was slain, I took it. Now it possesses my strength as well as his! It has slain sorcerers and demons; it has drunk deeply of the blood of hundreds of maddened warriors- so deeply that in and of itself it has become a potent magical weapon!"

"All of that is probably true," Osylla admitted, frowning slightly.

"I-I will give it to you," Sonja told her. "Or it, and myself, in service. Only-free Daron of your curse."

Osylla's eyes half-lidded themselves. Was she seriously considering Sonja's plan? Sonja stepped closer, her quivering left hand clenched at her side, her right holding out the sword. "I am this blade," she said urgently, "and this blade is me." Her voice dropped into a conspiratorial whisper. "This blade is more than a steel weapon. Feel it!"

Sonja held the blade out for Osylla to touch. The witch warily backed away a step, and made a rapid, intricate sign, and a faint yellow glow sprang into being around her.
"Think not to deceive me,” she said, “I am
protected by a sorcerous shield which no steel can penetrate."

“My weapon is yours. It can add greatly to the strength of your sorcery. Feel its power!”

 The witch was studying the blade; she reached out to touch it, allowed two fingers to rest upon its edge. "Indeed, there is a great strength in it. I might be-"

She looked up—

Looked up, into Sonja's suddenly fierce sapphire eyes blazing with the intensity of hate...

Sonja's left hand darted forward, fingers unclenching as she hurled the ashes of Odurac straight into Osylla's face. Instantly those ashes became a myriad of sparks buring into the witch's cheeks, lips and green eyes. Osylla gasped; the yellow glow about her flickered out.

Then Sonja's blade moved, still with the witch's fingers upon it. All of Sonja's furious strength went into that stroke. The witch, in her shield of power, might have withstood the strokes of a hundred blades, but the ashes had stolen all her sorcery. The sword's razorlike edge sheared off the tips of her fingers, caught her in mid-throat and plunged clear through her neck. Not even the bone could resist Sonja's angry thrust. Blood spurted as the witch's head toppled from her neck; her arms went limp and her legs buckled. Then her head, trailing the long golden tresses already wet with blood, struck the damp earth of her island, while the severed neck gushed scarlet.
- Red Sonja: Star of Doom