Umad

Okay 
1. Light hugging real space warships are deathtraps.  

That asside.. 

Larger. More mass. More fuel mass. 

More missiles, less secondary and optimise that to be sand caster/launcher heavy, drones or parasite craft will never have the p/w to do combat in this things regieme. All they can do is die in a sand blast. Your main CREW should go fusion gas
Laser with a few really impressively massive internal generators and a proper optical output conduit network and outputs. Loose most of the lighter crews.  This means your ladar pulses alone should be vaping subcraft.  

 
 Your primary attrib is your base ke. Moar dumb mass bombs! Mebe fractal sections of your ice amour. Loose the quad spinals and go with at most two larger nastier multiroles.  
Form wise a cone is nice and all buuut... 

A big brute of an ugly mushroom of dirty fuel ice up front in whipple formation. Also a brute of a set of em field generators / charged particle field systems. You need that all over.not least as at your speeds you can use every bit of interaction to change velocity and a deployable drag chute of charged particles interacting with a solar wind will help. Alot. 

   

1. EMP is not a kind of ammunition. EMP as in the effect generated by nuclear weapons doesn't exist in space either (no air).
2. EW suite weighs 50,000 tons... why?
3. Sabots are pointless in space, there is no drag and separating the sabot will require explosives (again, no drag). Which won't really accomplish anything anyways.
4. Arbitrary effective ranges are arbitrary. 200km? 20km? Why?

Quote from http://www.fourmilab.ch/cship/craft.html=

"rapier-like to pierce the tenuous birth-cry of the universe."

luv it

Since when is EW efficiency a function of EW suite mass?

HPM weapons are just one of many choices in the vacuum to burn circuits. In terms of electronic-frying potential hard X-Rays and Neutral Particle Beams are likely superior because they can induce electronic-destroying effects behind shielding.

Oops, just caught this!

EMP is an ElectroMagnetic Pulse, simply a big burst of any kind of EM energy; light, heat, radiation, whatever. But, in general terms, 'EMP' is almost always referring to a massive burst of EM energy in the radio-wave band. Nuclear fission, sunspots, and lightning are the most common generators of EMPs. They are harmful(or useful, depending on your point-of-view!) because radio waves induce electric current through any conductor they pass through. The conductors(circuits) in microchips are so tiny that even a relatively weak induced current can interfere with, or physically damage them.

Edit- In the late 19th century, a solar plume occurred so large that it would have destroyed every microcircuit on earth, had they existed. Astronomers believe these big bursts are a periodic occurrence. YIKES!

'Nother edit, might be useful to somebody- The most promising current EMP weapon concept uses a warhead that generates a pulse by explosive compression of certain piezoelectric semiconductors. (say that three times real fast!)