The weight

of a throwing knife is also important. Among
trained knife throwers, a well known approximate ratio of
one inch to the ounce is standard knowledge. Therefore, a
nine-inch throwing knife should weigh approximately nine
ounces, and a sixteen-inch throwing knife should weigh
approximately sixteen ounces. If a knife is too light, it will
have poor flight characteristics and not enough hitting
power.If a knife is too heavy, it is difficult to throw, has a
shorter range and is slow. An old Ninja maxim states that,
“A thrown knife should not fly like a feather or a rock, but
like the beak of a hawk.”
Last but not least, balance is another important factor
determined by a throwing knife’s design. It is inherently
related to the other two factors. The finest and most versatile
throwing knives can be thrown either by the handle or by the
blade. They are balanced exactly in the center of the knife.
Test this by balancing the knife on the end of one finger to
find its center of gravity.