Everything is just an object, it depends how you use it, which make's it deadly or not.
ie. a rock - you could use it to decorate gardens, make a mini dam, or you can make it dangerous by throwing it at someone.
In the end is it's down to the person using the object, and one thing us humans are good at is finding many ways to use those things - bad or good.
Banning things is not the answer because people will just find something else to use, while the people who enjoyed and used the object in a positive manor is left in disappointment.
Solution:
Ie; knifes - as they can't fully be banned, make strict laws that send a message, using them in a negative way will end up in harsh consequences.