I don't know what you have been trying to list, but, even with the correct delivery policy, you still have to comply with Ebay's knives policy.
Essentially, you can only list eating knives which are part of a cutlery set.
So, you would not be allowed to list a cake knife or an antique, mother of pearl handled fruit knife, for example.
Full policy is here:
https://www.ebay.co.uk/help/policies/prohibited-restricted-items/knives-bladed-items-policy?id=5047&...
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)