The Dawnguard Rune Shield is a uniquelightshield and a variant of the Dawnguard Shield. The "sun-shield" effect is similar to Stendarr's Aura, and has similar effects; however, no benefit is gained by using both the shield and restoration spell simultaneously. Stendarr's Aura cancels out the effects from the Rune Shield.
360 If the Dragonborn switches to this shield via a shortcut in the favorites menu (i.e. left or right on the D-Pad), the enchantment will no longer work. A known fix for this is to unequip the shield and requip the shield. (Confirmed 360, PC and PS3 unknown).