It could also be for the same reason the Jung ships of the line have yet to have energy weapons. They are keeping them for the home fleet. Maybe...
I had always imagined that the antimatter was stored in containment capsules (referred to in the series as “cores”). Each reactor has numerous cores, (4, 6, 8… I don’t know) and antimatter is pulled from each core as needed. That way, if a single core develops an instability in the antimatter containment field, it can eject just that core. That also means the resulting matter-antimatter event is that much smaller, in comparison to a big core. It also means that you don’t completely lose the function of that reactor, just some of its available fuel.
As to how much antimatter has to be carried, it’s far more than most people would imagine. While each core by itself might not be enough to destroy a planet, it would still do damage. All of them together…enough of the planet would be destroyed that it would become unstable enough that it would probably break apart due to the disturbance of the balances that held it together in the first place. Imagine what would happen if you suddenly took 1/3 of a planet away. What would happen to the planet’s rotation? Its orbit? Its atmosphere? It volcanic activity? Would its suddenly uneven mass cause it to spin apart and fling chunks of it out into space? Seems pretty obvious that any sizable matter-antimatter event would result in an unrecognizable/unlivable world.
How much antimatter you need to "destroy a planet" depends on how destroyed you want it to be. On the lower end, 50-1000 kilograms is probably enough to cause mass extinctions by being roughly equal to planet killing asteroids. To do real damage to a planet more-less requires filling up a massive space freighter with something like millions of tons of antimatter and slamming into the planet, which extrapolating from Wikipedia's page on impact events, is on the order of chunk of rock something 100-1000+ km in diameter hitting the planet.
If you know enough about a planet's layout and its weak spots, you could easily make things really uncomfortable (or even deadly) by simply targeting the "perfect" spots. Just saying. And I'm not talking about industrial or military targets here, but geologically "interesting" ones.
Just finished episode 12. Excellent!!! Kept me guessing until the end. Can't wait for "13". I also like the way your going with the series. BTW, I see you gave some clues as to the "Estimated" power of an antimatter explosion. (Massive?!?!)
However, if you use 1 g for acceleration, it’d take you nearly 1 year (354 days) to reach the speed of light – if that is even possible. 
And you’d have to calculate another year to decelerate from that speed to zero. Ideally, you’d keep accelerating until you’re halfway to your destination – to get there faster and to solve any issues with gravity.
OK, but here are a couple more things to consider. First, according to Einstein, the speed limit in THIS universe is the speed of light. This presents the question of if you were in a ship that travelling at the speed of light, what would happen when you tried to go forward in the ship? Would you be going faster than the speed of light or not moving? Also, What would happen if you were on the Outside of the ship?
Also, Einstein theorized that time would slow down as you approached the speed of light. Would it stop when you got there? How long would a trip to Alpha Centauri seem if you were inside the ship? Also, if time slowed down so much, would you really need a stasis chamber to carry enough supplies to make the trip?
One ever present theory about FTL is that it can't happen in this universe as we know it. Any form of FTL would involve stepping "Outside" this universe so that somehow the physical limitations could be bypassed whether it would be by wormholes, warp space, fold space, sub-space, jump space or whatever.
And here is another question. Where does the energy come from that is produced by a ZPED?
Well, according to Einstein, you're right. Maybe people couldn't move forward on a ship that flies at light speed already? Or maybe Einstein's speed limit is relative to the surroundings? Who knows? The one thing I know for sure is that I don't want to find out what happens if you're outside a ship traveling at the speed of light. Nope. Even in the near-vacuum of space, the mere friction alone might be too much for you to handle.
Different question, but in the same line of thinking: If light cannot escape a black hole because the black hole sucks the light particles back in - does light traveling towards a black hole in the first place get accelerated beyond its normal speed?
The subjective time on a vessel at c is also a very interesting point. And once again, I'm clueless. I have absolutely no idea what to base any assumption on. But... if it was possible to move faster than light, would it mean that, eventually, you'd move back in time?
Ahem, ZEPDs don't work. Scientific theory pretty much denies the existence of a ZPED.
(Matter at its zero point is at its lowest possible energy level. Since it's the lowest possible energy level, you withdraw any energy from the matter.)
What to do with a bottle of antimatter in a weapon. Use fields to cause the antimatter to scatter like a spray bottle. Little annihilation everywhere.
OK, but here are a couple more things to consider. First, according to Einstein, the speed limit in THIS universe is the speed of light. This presents the question of if you were in a ship that travelling at the speed of light, what would happen when you tried to go forward in the ship?
As anything with mass approaches the speed of light, that mass increases as well. The more mass, the more energy it takes to accelerate that mass. Stepping forward in an imaginary ship traveling at 99.999998 the speed of light adds no proportional increase in speed to yourself. However, just to accelerate a small spacecraft to that speed would take nearly an infinite amount of energy.
Note that typical Walking speed is about 3.7 billionths of the speed of light.
@richardh
Also Richard, it's not near infinite just largely impractical without being able to manufacture antimatter by the kiloton or some similarly effective power source. Wolfram|Alpha is rather handy here since it's got a nice relativistic kinetic energy calculator. Punching in the numbers and doing some unit conversions, it seems it just requires that at least 5 kilotons of mass (per ton of mass to be accelerated) be converted to energy to externally accelerate the spacecraft since it can't be carried internally at least without using a rather exotic power source.
