My wife has aquired an affinity to knives too. She now expects them to be sharp and will ask me to sharpen them if needed. When she does, I joke that she must be flirting with me.
Seriously, let her know that one is more likey to be cut with a dull knife. Since you don't want that to happen to her she should expect you to keep them sharp as a matter of course. Eventually she will learn to "respect the blade" and treat them all as if they wre razor sharp, until proven otherwise. I guess this is like people with guns treating all firearms they handle as if it were loaded until they prove to themselves that it is not.
Hope it helps.
Phil
PS : Maybe then she will have a new way to flirt with you.