Magical items are various types of items with magical properties in the series.
Some are able to help focus a wizards power. Others have innate properties. While others need to be innitiated. Harry Dresden is known to employ items like these owing to his lack of fine control over his power. It is not known how common these are among the general wizard populace.
Foci are specially prepared objects which magical practitioners use as tools in performing acts of magic. Some examples are:
There are other items items known to have other properties. Some of these include: leather that has been strengthened enough to be used as body armor; rings that are able to store energy that would be released as a wave of kinetic force; a thaumaturgical model of Chicago. The swords used by the Wardens have the ability to break any enchantment.
Some items, like the Wardens' swords, have to be individually attuned to its wielder in order to be used.
Harry Dresden has a silver belt buckle that contains a reservoir of energy that he uses to fortify himself in dire situations. He touches it and whispers: "Fortius". Then he gets filled with the life energy of magic; it can be called chi or mana. Dresden gets filled with excitement, hope, confidence, and feels ready to fight if need be.
Dresden's duster: the duster has been strengthened into what amounts to an extremely effective body armor. It is so effective that Dresden has crouched down and pulled it over his head in a wave of automatic gunfire. Side effects of the enchantment include it being unable to be stained and being waterproof.