What the Hard Light does...it's like all other non elemental weapons in the game, against element shielded enemies it'll do reduced damage than the correct elemental weapon. It does not penetrate the cabal phalanx shields, those are immune to all fire except burn abilities from grenades and certain melee's. What the over penetrating perk does is if you have a wave of thralls a single bullet will go through a couple of enemies. Granted each enemy pierced in succession will do reduced dmg...but some is better than none. I'd dare say it's better than the fate bringer in terms of close quarters with many enemies.