Fair point.
Another point of difference may be how the magic is used in the enchanted item. A Warden's Sword, for example, is basically passive magic. The magic used basically improves the quality of the sword, causing it to be capable of inflicting more damage -- but when someone swings the sword, they aren't releasing a spell. A mind-reading enchanted item would be an active item, in that you would trigger the item for effect. (Yes, I understand that a Warden's Sword has limited uses per day, but this is a balance mechanic more than a release of magical energy.) Shapechanging, by the way, is similar to the Swords in that respect: magic is used to alter one's body, but there is no magic inherent in the claw strike once the transformation is complete.
So perhaps that would be a useful standard: if triggering the enchanted item results in a spell being cast by the item, then it could count as lawbreaking, whereas if the magic is considered a passive benefit (even if it happens to have limited charges that are used when the player chooses to use them) is not.
If this standard were used, then you could have, for example, an item that alerts you when someone near you has hostile thoughts toward you. As a spell, this would break the law, but as a 'passive item' effect, it might not. Of course, the Warden's might disagree with this logic.