Look, let's get real here. The mouth-breathing semi literate thug with the neck-tattoos and the pitbull isn't an owner-occupier. The chances are he's housed in council or housing association rented accommodation. He has no right to keep a dog unless at the landlord's consent - or face eviction.
The answer to 'weapon dogs' isn't yet more unworkable legislation from the central State, it's for councils and social landlords to do their job.
If you really want a new law, then bring one in that jails the Chief Executive of a council or housing association for thirty days if a weapon-dog from one of their properties attacks someone. I guarantee that within weeks the problem will have all but disappeared.