IMO a knife is the wrong weapon for you to be using as a security man in a store. Trust me, I have done security work so I know a little about what I am talking about.

Think about it, are you really prepared to get into a knife fight with a shop lifter, in the middle of the store where you work, over a stolen pair of jeans? Two outcomes - He wins, and you are stabbed and cut up. Or you win, and you are now standing over a screaming, bleeding shoplifter, with a BK14 in you hand and blood all over your uniform. Have fun in court. Hey, the store got the jeans back.

Leave the knife at home. If you really think you need to be armed get a telescopic baton, but you better make sure you clear it with management first, if only to legally cover yourself if you ever have to use it. And get it in writing, or the day you have to use it on some junky, and he then tries to sue you (which he will) your employer will drop you like a hot potato and cover their own butt.