I think it all depends on your understanding of focus items and enchanted items.
For focus items, you could look at them as tools the wizard creates of his own volition, in order to refine his spellcasting, but to me, that is only one side of the story. Focus items can also be things that bring you closer to your magic, which in turn can increase your power. An item that you have an extremely emotional attachment to, for example, could work like that.
Enchanted items can be viewed differently as well. They are usually looked at as stored spells, and I know that's how the rules describe them, but you could also look at an enchanted item as a sort of focus item, that simply allows you to cast a spell a bit easier. So easy in fact, that it is less strain on you noggin', hence you don't take casting stress until you have to expend the uses with mental stress.
It's a mechanical representation, after all, and you can interpret it a number of ways. I would not categorically say that one or the other wouldn't be possible, but in fact make it depend on the character in question. A good justification for one character can be totally inappropriate for the next and vice versa.
While on subject, do you have to design your enchanted items before playing? I know that for foci you can do it during playing and for potions you can roll Lore to declare it. Do you also have to roll Lore for enchanted items?
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Again, it depends on the character. Often, though, if the player isn't sure about what sort of enchanted items he likes to have, I'll allow for them to be left open and filled in during the game. Much like potions, but without the roll, and they're for keeps until a milestone.
Also, what is focus specialisation?
A focus item can only hold a number of focus item slots equal to your lore. Since you can only use one focus item per type and spell you cast, you can at some point reach the limit of focus items you can use. With a specialization like that, you can expand on that. Though I have not seen anybody do this yet, the default capacity for focus items is enough for most.