Proof is need to comply with UK law, that a member is over 18, when buying or selling any bladed item on eBay.
The only way eBay allow this verification of age, is for a credit card to be presented at time of sale, or at time of buying, as credit card companies have already done very stringent checks to ensure that person is over the age of 18, so eBay have ' piggy backed' if you like , taken their verification processes to use for their own.
Anyone of any age can own a debit card.
You may be over 18, but this would not prevent a minor using your account to buy a bladed item, hence the asking for this, at time of purchase.
It is annoying I fully understand, not everyone has or wishes to own a credit card, my parents never had them, but this is the only way, the cheapest way, for eBay to act within the rules, for selling any bladed item online.
The only solution you ask, is if you need to buy this item from eBay, to ask a friend or family member who does have a c. card on file to buy this item for you.
@david-laurence