Age verification for buying knives online is “a huge vulnerability” at sale and delivery, a review has found, with thousands of weapons also sold illegally on social media.Metropolitan Police Commander Stephen Clayman, who is the national lead for knife crime, said it is sometimes harder to buy paracetamol than it is to buy a knife.The Home Office announced a raft of anti-knife crime plans on Wednesday, including making retailers report bulk or suspicious sales to police, and increasing the jail sentence for selling weapons to children, or illegal blades such as zombie knives, to two years.