Wand of Swiftness is a super-rare staff weapon. It is non-craftable, and exclusively obtainable through the Guild Shop or boss portal, for 300,000 marks or randomly via events (gold festival event at 2 million gold spent or dragon stage X).
Wand of Swiftness is the only wand to offer cooldown reduction. As such, it is perfect for a hero who specializes in utility and doesn't have much of a need for offense or other stats. This is why it's widely regarded as the best wand in the game for the Witch, and well worth the 300,000 guild mark investment to obtain one of these for her.
It's not particularly useful for other wand-wielding heroes, as the Warlock depends on damage and the Sorceress should only use this wand near the start of the game, otherwise only Graymarrow Wand for her damage.