Real knife from the Zhou period.

 The knife coins

The origin and dating of the knife coins are much easier than with the spade coins. There is no doubt that the knife coins were imitations of real knives, and they were used as mediums of exchange. The knives that has been excavated looks much like the early knife coins. They were slightly bent and had a ring at the end of the handle. Wang supports the believe, that this kind of knife was not a knife used as weapon, but was a kind of knife mentioned in the ancient text Zhou Li called a xue (Wang does not give us the character). It was supposedly used to whittle wood or bamboo (p. 145). 

The dating of the large knife coins of Qi, is a matter of the dating of the founding of the state of Qi. We know that these coins came from Qi because it was written in their legend. Wang takes a look at several views but argues, that there is not enough evidence to determine the date exactly. He concludes that the large knife coins of Qi were made between 1079 B.C., and as late as the first half of the ninth century B.C. (p. 153). There were other kinds of large knife coins, but there is no sources about the states that made these knife coins. We can only say, that they were made in the eastern states of Jimo, Anyang and Tan.
There were three kinds of later knife coins: the pointed knives, the Ming knives and the small knives.
These types were smaller, thinner and fragile, and had fewer or no characters on them. 

The Large knives were cast in the eastern states between 1079 B.C. and 1000 B.C.

The Sharp pointed knife coins were smaller and lighter than the large knife coins. They originated in central Hebei (p. 164) not earlier than 430 B.C. (page 148). According to Wang, we know that the small knives of the city of Lin were cast in the end of the Zhou period around 300 B.C., and the pointed knives between 400 B.C. and 300 B.C. Lin was a city in a border region, and these coin types could not have originated so far from the more central cities. Thus we can safely date the pointed knife to the fifth century or earlier (p. 175). 

The Ming knife coins were from the Warring States period, and is the most numerous kind. They all have the character ming on the obverse. On the reverse can be found serial marks and or place names. They have been excavated by the thousands in areas scattered over all parts of China. There were three types of Ming knives with differences in shape and style of character. They have been found in Hebei, Shandong and Shanxi, but also in Manchuria and Korea. A table showing the distribution is found in Wang page 170. Wang states, that although there is lack of literary sources, it is not far off to say that the Ming knives can be dated to the beginning of the Warring States period. 

The small knife coins were the smallest type with a completely straight back. They had no numerals or serial marks as the earlier types had. The legends were always city names. Small knives were cast in central and western Shanxi and in southern Hebei.

As stated above, Wang says that we know that the small knives of the city of Lin were cast at the end of the Zhou period around 300 B.C. Since Lin was a city in a border region, these coin types could not have originated here. Thus Wang dates the small knife to the fourth century or earlier (p. 175).

Drawing of a 32 cm. long knife (White p. 35, 65).

Further reading on knives:
Coole, Arthur Braddan: Ch`i heavy sword coins and debatable pieces of the Chou Era. 1976.
Coole, Arthur Braddan: State of Ming knife coins and minor knife coins. 1976.
Coole, Arthur Braddan: The early coins of the Chou dynasty. 1973.
These books have rubbings and pictures of very many types.