Butterfly knife

Butterfly knives are sold as a pair for 2 G.P. under miscellaneous weaponry. Each weighs about 1/2 lb. and deals 1-6 damage, with no minimum Strength.

The book cites them as an example of paired weapons. Once a martial artist reaches 8th level, he or she can elect to learn such weapons, and wielding them doubles that character's attacks per round, the same benefit the Hand Strike technique gives.