Torpedo and stun crystal are perfect.
The polaron shroud on the seeker needs to fade out more near the tail, and/or spread farther from the weapon's body.
For the bio armor, the greenish armor has the better camera angle. Try moving the camera to the right a bit, so there's some horizontal overlap. The textures look great, and for some reason, the shape reminds me of teeth. A very nice effect for boarding defense
For shield armor, I'd prefer a more colorful armor part (grey dosen't seem to fit with the rest of SE4). Some sort of discharge between the prongs would be nice. What would be really cool is if the discharge formed into the rough shape of an SE4 shield generator.
Three arcs of energy, and a glow in the middle...