I agree that the shield of the pistol is overpowered. The enemies are not smart enough to attack you from the flanks or from above in case you have that shield. The shield would have to spend ammo, maybe accompany you and be destroyed after a few hits.
Talking about the overpowered shield? Not only that not a single shot hits me, the boss kills himself when he comes to close. https://vimeo.com/835370915?share=copy