Outfit is vital to the character. With your bare hands it is not possible to catch an arrow or to beat off an ax with your trained chest. But armor is powerless against magic.
Equipment has requirements and qualities.
The requirements determine which characteristics of the character must be sufficiently strong in order to take this item. The magician can not take up the heavy armor of the warrior, and the warrior will not have enough knowledge of magic to use the magic staff.
With qualities everything is simple – weapons cause damage, armor protects, amulets defend from magic.