A neat idea lifted from Sea of Stars is a Paper Charm that gives the target better armour (that’s armor for you North American folks) by Sean Holland. In the example the AC is improved moderately, which implies the effect is overall shielding the target from harm; a form of damage reduction in non-DND speak.
The priestess walked slowly down the line of nervous villagers, each clutching a simple tool that they hoped to use as an effective weapon. Stopping in front of each, she placed a charm against each villagers chest and in a second, they were clad in white paper armor. While the protection the charms gave was limited, it gave the villagers hope that they would be able to stand against those who would harm their homes and families.
These paper charm are marked with the symbols for protection and safety. When the command words (or prayers) are spoken and the charm is placed on a person, it unfolds into a suit of paper armor to protect them for a short time.
The armor has no weight and causes no penalties, it lasts for three hours and then dissolves into a handful of shredded paper.
Here is the same effect written up as a device with charges (in effect a temporary magic device) for Ars Magica.