Knife coin legit?

Hello everyone interested in purchasing this knife coin advertised to be from the Zhou dynasty. Is it authentic? I have no experience in Chinese numismatics. The dimensions are 139 mm X 20 mm and a weight of 17.68 grams. Thank you in advance for your help. 

It is authentic. The type is Ming knife 400-220 BC. These knives are the most common type of knives. There are many reverse variations, that is many different character variations. Value range approximately 30-60 eur. 

How can be sure that is authentic with so many being sold very cheap every day?
https://www.aliexpress.com/i/32846477475.html

I have heard  almost 99% of every spade money is fake and the authentic ones are in museums.

Those Aliexpress ones are totally different and very easy to say that they are fakes, their appearance is not correct, their characters are not correct etc. 

Ollisaarinen

It is authentic. The type is Ming knife 400-220 BC. These knives are the most common type of knives. There are many reverse variations, that is many different character variations. Value range approximately 30-60 eur. 

Best reply I could ever get, thank you very much for your insight

Only accept it with a COA signed personally by chairman mao