apotropaic, a word which hopefully I will not need to define for you when you get round to revisiting this
the concept of casting a spell in and of the process of baking bread, and whether the spell worked or not, well, we’ll have to wait and find out, but in the meantime, we have bread
First aid kits are charms against getting injured. Tire patch kits are charms against getting spare tires. Not using them does not mean they are not needed, it means they are working.
Some charms get used up faster than others. This means they need replaced. This is what happens when you lose something, or when you need the supplies. Imagine all of the things it protected you from before this happened!
Spellbooks, grimoires... they are instructions for doing things well. Most of the time they are printed as textbooks. Sometimes they are in fact lost tomes, because people said, “using honey on burns is superstition and we don’t need that anymore” and then it turned out that there were in fact reasons to do that. Studying magic is sometimes an alchemical process, and sometimes a process of twisting one’s brain to figure out why that worked.
Being a purveyor of charms means you can put these things together, but sometimes also that you know what sort of charms someone needs. Sometimes this is telling someone they need the first aid kit with the tweezers in. Sometimes this is because one of the workers in the household is a carpenter.
the concept of different forms of luck, a la The Long Ships. Perhaps the concept of one’s fated death, perhaps not. That’s a personal choice.