The Vorpal Blade is a fictional sword of amazing power. The term "vorpal" first appears in a poem in Lewis Carroll's Through The Looking Glass. In the poem, later released by itself under the name "Jabberwocky", a young boy wields the vorpal blade and slices off the head of a monster called the Jabberwock. In truth, "vorpal" is a nonsense word, one of many Lewis Carroll invented for his surreal stories.
In the pen-and-paper RPG Dungeons & Dragons, "Vorpal" is a magical property that can be added to a magical bladed weapon to give it the ability to slice off the head of an enemy in a single stroke. In essence, this allows a chance for an instant-kill attack.
The Vorpal Blade appeared in American McGee's Alice as a nod to Lewis Carroll being its source. In Alice, the blade was a butcher knife that could be used for a slashing attack or be thrown at enemies to deal moderate damage, to magically return to Alice's hand seconds later. It was the first weapon obtained and the weakest overall, considered a weapon of last resort as neither of its attacks used up Will energy.
The Vorpal Blade returned in the sequel, Alice: Madness Returns, in which rather than being a weak fallback weapon, it was Alice's primary weapon throughout the game, serving as her go-to attack when dealing with the hostile creatures that plague Wonderland. Like all weapons it could be upgraded three times, and though the physical appearance of the Vorpal Blade remained unchanged, the colour of the glowing trail the weapon leaves in the air when swung would change with each upgrade, ultimately leaving "glowing" black energy in its wake.
The Castlevania: Symphony of the Night rendition of the Vorpal Blade is a one-handed sword that is strikingly similar to Hiryu's primary attack in Strider: a white wave emits when swung, and it can be used rapidly while moving. There are two other weapons with an attack like this in the game: a shorter ranged version called the Holbein Dagger, and a four-burst-fire version of the full sized blade called the Crissaegrim. These weapons are often considered to be overpowered due to how easy the game becomes after finding the drop. In the Japanese version, the Vorpal Blade was known as the Sonic Blade.