Brilliant selections I would say. You're so right about the key rings. I took up your challenge - turns out I have both your first and second item on my key bunch and even a bottle opener. It's always good to have a small knife on your keys, you have no idea how often I use that knife! It comes in super handy. I know what every key is for - I don't hold onto keys that no longer have a use - they get thrown into the recycling.
Have a great weekend!
I think that the thing about knives is like lighters (why didn't I put it in?), You can't imagine how useful they are until you need one, I have a friend who was a smoker before and although he has already stopped smoking, he still carries his lighter and I asked him once why he did it and he said "it's more useful than you think", and then I borrowed it to light the grill because my match sticks got wet hahaha