Depends.
In my homebrew their are two types of magical weapons and armor. There those that are created by wizards via the normal means presented in the core rules (which are perverted forms of magic, according to the setting rules). There are also magic items that are "legacy" items. The Legacy system is similar to the advancement of the samuri's weapon in Oriental adventures, except that it takes a whole lifetime to add 1 special feature to a weapon. Like the OA rules, a young warrior with a powerful weapon can not use it's full power.
So, if you have a sword, or some armor handed down to you from your great grandfather who was a mighty slayer of orcs, through his son who was a great leader of men in a war, to your father who was remarkably strong, to you, you might have a sword that grants you bonuses against Orcs, bonuses to your Leadership score, and a small magical Str. bonus (maybe once per day you can call upon your father's Strength to aid you).
This is pure or "clean" magic which does not fade in time. Since the campaign setting is over 8,000 years old, there are some ancient swords and armor that are extremely powerful, having been carried by dozens of heroes throughout the ages.
So, "Legacy Items" usually have a long and detailed history, such as the Blade of Might. But "Forged Magic" items are usually created by wizards and don't last long enough to have a noteworthy history.