to flourish a sword in sword dancing so as to produce a whistling sound
About the Word:
Whiffling may have its origin in the efforts of ancients to clear the dance area of evil spirits. Not every dance area, of course: sword dance areas.
Sword dances traditional folk dances featuring men and swords have a long and glorious history. These days, you can see (and hear) whiffling in the circular "guerrilla" dances of Turkey and the Balkans and in the Balkan "rusalia" fertility dance.
By the way, the trademark "Wiffle Ball" omits the h.