I used to work for a local chain of agricultural stores, which had no stated policy. After a co-worker injured himself through the careless use of a knife (a SanRenMu 710 I had gifted to him) - and the company had to pay for his medical bills because he was on the clock - they started talking about banning knives at work.
So, I knocked on the owner's door, stepped in, showed her a rusty utility razor blade and a clean folding knife blade, and asked her which was going to cause a larger medical bill if used carelessly. The rusty blade would cause an infection and create an irregular and jagged wound, possibly breaking off fragments into the tissues in the process. The clean knife (the very same knife involved in the aforementioned incident) would/did cause a clean slice that is/was much easier to clean, stitch, and heal.
Without a word, the policy went away.
I'm not saying that'll work at a larger chain or a more corporate setting, but I just wanted to publicly pat myself on the back for being the Knife Ambassador at my old job.