Annisa is resorting the metals by trade value. The pewter's not worth much; these impure irons aren't either, because you'll have to separate them out and that's a chore only some students will be down for; the nickel is solid and the purer irons and the steel are good. "So it's not actually a sharp distinction, right, especially not in here. Items that you brought in from the mundane world will pick up personalities eventually, the way things behave will depend on intent and force of will as much as on concrete features they have.
Artifice is kind of just - imparting that intent and force of will deliberately rather than accidentally, filling the 'what-this-object-is' rather than leaving it to be filled in by whatever intents happen to be around. It's mostly done by incanting as you make the item, by having the work you put into it be very directed and very intentional - the reason mundie items are so vulnerable to going bad is that they're mass-produced in a factory, no intent for them to pick up at all. Wizard-made things go bad much much more rarely. If you want something to be powerful, then you're putting a lot of effort and intent into it, and a lot of mana, and it's important for the intent you're putting in and the mana you're putting in to be sort of commensurate - you can't rush a major artifice project by stamping a knife from a preexisting mold and then dumping an enclave's worth of mana on it, you haven't done anything to communicate your intent. So generally speaking what you do is have your aim in mind from the start of the project, very specifically, if you're confused about anything you're going to have a problem - if you discovered midway through that you were confused about anything you're more or less going to want to start over - and you incant over it, and you put mana into it where appropriate, and you try to build something mundanely high-quality enough to feel appropriately commensurate with the magical intent for the project, and you make sure that at every stage of the process your work in progress is well acquainted with your vision for it.
You can make very powerful magic items by, like, planting cotton and tending it and harvesting it and separating it and spinning it and weaving it, singing the whole time, all full of intent to make an outfit that will be powerful or fascinating, because that cotton from the instant it starts to exist knows what it's for. There's not exactly an equivalent for metalworking, metals are all much older than us, but an alloy you made yourself is a little better than one you found on a shelf, for steel it's best to do it yourself from iron, and there's endless opportunity for guiding it while you forge it and grind it and fit it and polish it.
With practice, artifice gets to be kind of - a conversation? You can feel where your intent isn't translating right, where your knife isn't shaped quite like your intent, and figure out what you're miscommunicating."