My Wing Chun instructor recently bought some Hanwei butterfly knives, a traditional Wing Chun weapon. He was very pleased with them, and with his cooperation I've published a review of the blades.

http://philelmore.com/martial/butterflyhanwei.htm

It took me a while to figure out that Hanwei (http://www.casiberia.com/hanweiknives.html) was a company, not a style of butterfly knives!

Sorry about that. ;)

You can buy these butterfly "swords" directly through my school, Syracuse Wing Chun (http://www.syracusewingchun.com), if you're interested. Sifu Anthony Iglesias also sells those little single-section wall punching bags I reviewed earlier.