Combined
A combined item is actually multiple items combined into one. Only one item can be used at a time, and you can switch modes with the item while wielding it as a swift action. The base item is the default mode which is always the single most expensive of all the items combined.
The combined item's cost is equal to the sum of all the included items +50%.
The combined item's weight is equal to the single heaviest item's weight +50% the weight of all other items combined into it.
The item has a combined pool of charges, requiring ammunition unique based on its combination but using the same ammo for all included items. The item with the smallest ammo pool and longest loading time determines the combined item's ammo pool and loading time.