That's interesting, Old Grump, because I completely disagree with you.
The cleaver is designed to cleave, using either momentum or a rocking pressure. It is only a threat in one direction, more or less.
The skillet relies purely on blunt force, and requires some room to travel in order to be a threat.
A good knife is a threat at the point, in one direction; but its blade is designed to cut by slicing, and it doesn't require much relative speed in order to inflict a deep cut - and since its travel is easily reversed, it's a threat in multiple directions.
Having practiced thousands of counters vs different weapon types, blunt weapons are the simplest to counter - don't try to block, per se, just step inside the arc, right up to the wielder, where the inside radius doesn't allow much speed on the weapon; unidirectional threat types such as cleavers are the next simplest; but knives can be a real pain.
You have valid points and I agree a knife in the hands of somebody who knows what they are doing is bad medicine 'BUT', you knew there was a but coming didn't you?
I have trained against unconventional weapons and trust me, I will take my chances against most people with a knife rather then try to stop a cleaver. An untrained man or woman with a skillet and I suggested 10" over 12" because of the weight issue only needs to hit you once to hurt you, arm broken, forehead flattened, sideways swing into the ribs will double a person over right nicely and it will be awhile before they can stand up straight again. A man fighting for possession of the protagonists gun won't even see a cleaver coming till it's to late.
I'm old and slow now but it used to be the instructor would keep me off the mat when he was trying to teach a technique because I cheated. I still cheat. The last punk kid that pulled a knife on me got a whack on the top of his head from my cane, second swing got him on the forearm making him drop his knife and when I swung the third time he was out of range and moving down the block a lot faster than I could run.
First time I grabbed the wrist of the kid with the knife and squeezed till he dropped it. The second two, a New York tough guy got kicked in the chest and lost his knife. the third guy, a Chicago punk, got kicked under his left eye and lost his desire to continue. I'm just a simple farm boy and don't know all the fancy moves or names of the moves but I grew up fighting and never really stopped. Other than formalized fencing, boxing and wrestling all my fighting was in the street figuratively speaking and I did learn a couple of things along the way.
One thing I learned is me and a 16" nightstick would have bamboozled most every knife fighter I ever come up against with two exceptions. One a little Filipino fellow I was happy to be friends with and the other was my Marine partner on Shore Patrol.
Back to the OP's sister she now has an easier to handle knife and if it gives her a confidence factor to have it that will do her good in time of need. Chances are she won't need it but if she does I won't want to be the boogerman. Hopefully she gets some martial arts training to go with it.