The following were mentioned as WMD's in Freelancer.
Fusion/Antimatter Bombs - The Order regularly made use of these, I believe a fusion bomb was used on a Cruiser in Z21 destroying it instantly. Also, the explosion was visible from Norfolk.
Thermonuclear Weapons - Fat Man exploded with a blast radius of nearly FIVE Kilometers. Our nuke mines explode something like what? A hundred meters. If anything, the amount of radiation and destructive force they make is barely anything and is likely just caused by other components within the bomb with the added uranium for extra, umph.
Now imagine a type of Nuclear ICBM type Warhead cruising towards you that has a VERY VERY powerful yield as it's space, and watch it wipe out some twenty kilometers worth of space. You can hear Kusari warming up nuclear weapons against Rheinland and Bretonia on the CNN.
There are also unknown but still highly destructive bombs that are capable of being loaded on transports that can destroy Battleships should the transport manage to ram it or get close to it.
There is the neutron bomb which basically annihilates everything with intensive radiation. There has been reference to biological weaponry that are capable of doing pretty nasty things.
I can also imagine Plasma rays that are capable of superheating planets and similar things, 'glassing' them and rendering them uninhabitable as their atmosphere can collapse.
NNEMP (EMP) weapons probably exist as well, and considering the extent I don't think that it would simply just effect machines but likely kill anyone or atleast give them one hell of a shock.
Thermobaric bombs can also be used to a very shocking effect in certain areas thus giving them WMD power.
Kinetic Energy weapons can also be used to similar effects to Nuclear weaponry. A proposed design of a Satellite launching tungsten infused steel rods (or was it tungsten infused with steel?) down at earth was projected to hit the earth with enough force to create a blast as powerful as a tactical nuclear weapon. I can see a Gauss Cannon, or more synonymously a MAC Cannon from Halo utterly annihilating a few things.
Tiberius Walker, putting flames out and being awesome since Apr 13 2008 ™
[8/17/2008 5:56:46 PM] Aaron (Boss/Jurgen) says: Can't bring myself to say it... Looks like you get the LABC, I've seen what you can do in one
Walker (Albert Wint): I can has win? --- Epyon the Bored: You can haz win. --- [1:18:00 PM] Chris (Niezck) says: I love you <3
[5:55:53 PM] Raisu says: Walker pwned both Battleships(LNS-Texas LNS-Arizona) - [5:55:57 PM] Raisu says: in a cruiser Tiberius Walker, spreading mayhem, destruction, and Spamming Flood since Oct 22 2008 ™
[9:08:25 AM] Gurjiv (Frozen) says: I hope someone gives you AIDs.
[7:15:17 PM] Dylan (Ximen) says: Walker... you have no idea how much fail you bring into this world...
[8:05:08 AM] Ross (SevereTrinity) says: Screw you for making me install FL again
[10:51IE AM] Epyon the Bored says: My god if I ever meet you I am going to strangle you. Tiberius Walker, being better then you since April 30, 2009 â¢
We will remember - We do not Forget - We do not Forgive
IE AM] Epyon the Bored says: My god if I ever meet you I am going to strangle you.