A-PAWS kill a ship if they hit it. "Zap"
The amount of antimatter "payload" that an A-PAW could accellerate to relativistic velocities would be in the milligram range at best.
Since the hull armour on many MT ships could arguably *take* a contact hit from a nuke (see note below) this struck me as silly. Even more silly was the fact that A-PAWS appeared before antimatter warhead missiles. This led me to the conclusion that "zap guns" were cool (sell product) but logical extensions of physics were too uninteresting to add.
(math warning)
Admittedly 1 mg of antimatter should result in a about 90 gigajoules of impact energy, but at relatavistic velocities (.99C+), 1 mg of *anything* will result in 45 gigajoules of energy (e=MC^2 for your "conversion" energy , Ek=1/2MV^2, V~C, Ek=1/2MC^2) At "best" you triple your impact energy, but this would be at the cost of a lot of fancy gear to ensure you didn't blow your PAW to bits with any "remnant" antimatter, and I'd be really interested to see how they get 100% "perfect" recombination when converting the C-PAW to an N-PAW for vaccum use. This is less of an issue for a "normal" PAW, since you probably don't care if you collide with a few charged particles, but is more of an issue when those particles are so "energetic" (Perhaps twin PAWS, one negatively charged, one positively charged)
(/math warning)
The pragmatist in me suspects that simply making a bigger N-PAW would give you the same effect for less cost and less risk. If you're willing to take the risk, why not use missiles with a real payload (grams to kilograms) of antimatter: a 1 g payload kicks your contact yield to 90 TJ (alomst 10^17 J) and a kilogram gives you another three orders of magnitude. At the tech level available, powering the missile with a fusion reactor capable of doing the containment is a no-brainer (See the HEPLAR missile designs starting at Tech-13, all powered by a fusion plant) and I bet you that it's a lot more cost effective to fire 1,000 missiles than to build a platform capable of mounting an A-PAW. My current (T-13) missile corvette design should be able to cram in about 80 missiles (I'm still tweaking the design) on a roughly 300 Td hull: that's 12 300Td corvettes against the cost of a massive battleship

We can do an analysis on the number of corvettes and missiles the BB can kill, but I'm pretty sure that 3 missile corverttes/kiloton of cap ship (or more accurately, 240 nasty missiles/Kton of cap ship) will make life difficult for the capship.
And yes, I'm trying to slant the universe (at least my universe) back towards the "small ship" universe of yore, but this is a big part of the reason that (non-carrier) naval combatants has shrunk in the post WW-2 era: if one missle can take out your ship, then more, smaller ships are a better idea.
Note on Nukes in CT/MT:
Since CT/MT didn't have bomb pumped lasers, they had to assume that you were really lobbing nukes at each other. Have you ever tried to kill a cap ship with nukes using HG? it takes a LOOOONG time if said ship is armoured.
Scott Martin