Aside from the Mobs, there are other interesting pieces.
Weapon and Armor Templates are a nice idea. Modifiers for an item based on where and/or by whom it was made. Feycraft, Hell-forged, Soul-forged, and so on. An item can have one template. Each Template can adjust the qualities of the Armor or Weapon (there is a separate Template for each), and adds one or more "affinities". The affinities make certain armor or weapon magical abilities less expensive to add to that weapon. They also impart a special ability to the user.
Each template increases the cost of the base item (at least, I have not noticed one that decreases it).
Feycraft armor, for example, costs 500 gp extra, weighs less than normal, has reduced hardness and hit points, has reduced arcane spell failure chances, has affinities for the glamered and silent moves abilities (among others), and gives a morale bonus to the user's bluff checks (because the beauty of the armor increases his/her confidence).
Adjustments to hardness and hit points are less meaningful if the DM does not make Sunder attempts or track damage to objects. In such campaigns, it might be necessary to disallow some of these templates, or increase the price modifier.