The Party Storage Chest is the only container that can be used to store party items in Dragon Age: Origins. It requires the Warden's Keep DLC and can be found at Soldier's Peak after completing the DLC's main quest.
The chest is an additional storage space, with a capacity of about 90 (the same as your party storage.) It is right next to Levi Dryden at Soldier's Peak.
- Some weapons and armor that are left in the chest will be re-scaled (see Materials) to the Warden's current level. This can be used to "upgrade" a favored weapon or armor that was picked up early in the game. This will only occur with items that have multi-tier versions; unique items such as the Juggernaut Armor only have one version. Low-level Wardens should be cautious when placing items in the chest, as it can also downgrade them.