Definition - to flourish a sword in sword dancing so as to produce a whistling sound
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. In case you were wondering, the trademark "Wiffle Ball" omits the h.
The word whiffler, although closely resembling whiffle, is fairly distinct. It has meanings such as “a person who frequently changes opinions or course,” and “a person who uses shifts and evasions in argument”; the origin of this whiffler is from an obsolete word for “battle-ax,” wifle.
On page 9 we see a good technical term, “whiffling”—the sound made by flashing swords. Eagerly we read on and are told that war dances grew out of herdsmen’s need for new land.
— Gertrude P. Kurath, Midwest Folklore, Fall 1955