One could simply clear the large hall before the fight with Velstadt, and continuously ring the bell beneath the staircase to continuously farm for the shield, as it would not require the use of a Bonfire to respawn them. Simply ring the bell once more, whenever the Apostles are dead, to spawn additional ones.
The Magic Shield, as the name of the shield may imply, boasts excellent elemental defenses, and the highest base magic defense of any shield in the game, while weighing only 2.0 units and having an appreciable physical damage reduction. It can also deflect spells with a parry, though the window is marginally-longer due to the animation.
While it may seem like an excellent shield for countering mages and the like, it also possesses a dangerously-low stability, being much lower than most other small shields, save for the Foot Soldier Shield. One should be cautious not to block one too many attacks with the shield, as their guard will certainly break easily if it is overworked.