You can find eBay's policy on age restricted items here: https://www.ebay.co.uk/help/buying/default/age-restricted-items?id=5596&st=3&pos=1&query=Age%20restr...
I was surprised to learn that a hedge trimmer is now covered. eBay's policy has clearly moved beyond just knives and other bladed items that can be used as weapons. For example, they now even includes food processors - and I don't imagine that many assaults by food processor have been reported.
eBay's definition now seems to include items which could be unsafe for anyone below 18 to use. And a hedge trimmer can be lethal to little fingers!
Unfortunately, I think eBay only accepts a credit card for age verification for bladed items. They accept age verification through VerifyMyAge for "many items", but I doubt this extends to bladed items. You could ask customer support.
