Would it help to challenge yourself to stop carrying the knife with you?
Rationally: How many times have you taken your dogs out and not needed it?
Psychologically: safety behaviours have a way of reinforcing anxiety (as opposed to fear). Each time you pack your knife? You’re sending your brain the message that you might need the knife. And likewise, each time you don’t take your knife, and come home safely, you help reset the brain into understanding the knife is unnecessary.
Legally: I think it’s probably not legal...?
Practically: the knife is in response to anxiety about a particular person. But, if you were to see that person, you would no doubt do a quick u-turn, right?