Each class has different and same skills with other classes.
Players don't need spell books to learn the base class skills.
Although there are some rare and epic skills, that can be learn by any class from their book.
Every character can have Max 1 class, the base one.
To play another class, you need to loot or buy the item that changes the base class, or just create a new character.
Also each class have attack skills, so they won't be boring.