Plasma Accelerator (ignores 60% of shield resistances, also hull, armoured bulkheads and completely the hardness)
edit: added:
Phasing sequence experimental effect, it can be applied to pulse lasers, burst lasers and plasma accelerators. It makes a small portion of damage bypass the shield and directly damage the hull.
Remote release flechette launcher: a miserable attempt at shield tank balancing: it bypasses shields entirely and damages modules directly.
Reverb cascade experimental effect: applies to mines and torpedos. It bypasses the shield and directly damages the target's shield generator.