Weapons hardpoints, like any other type of hardpoints need to be attached to the primary mesh...
By example, if you wish to make a ship who is half transparent like these in the "earth final conflict" series...
You create first the "shape of the ship"... in XSI, you add all the weapons/abilities/flare/exhaut/etc... now, you shave only the "shape of the ship", without the hardpoints... in XSI, you delete "the shape of the ship" and keep only the hardpoints... you create a new mesh model, by example a cubus... make it so small that you cannot see it ingame... add a new particle hardpoint at 0,0,0 that we will use for call the "shape" of the ship via particule effect...
In game, the ship mesh with hardpoints will be the cube so small that we don't see it... these cube will have a special hardpoint who call a particule effect who generate the real ship ( "shape of the ship" mesh ) with half transparency... for more realism, the cube can have a second special hardpoint for a third mesh ( internnal ) using a light emitting particle effect... for the moving light inside the ship, usual particule effect can be used with hardpoint located inside the "shape of the ship" but attach on the non visible small cube...
Point is that the primary mesh can be a dummy mesh, something so small with only a few poly ( triangular pyramid use only 4 triangle ) that you don't see it onscreen... particle hardpoint will attach to these dummy mesh... by attach, i mean being part of the mesh, there is no need to particle point to be in contact with the dummy mesh...
Method have a few minor problems... first, in shipyard, you will not see the ship being build since particle effect is only activated after the launch of the ship... when other ship fire at it, the target is the no visible very small cube, so weapons effect and explosion will appear to happen inside the ship when shield is down or when they go trough the shield...
You need to manually edit the .mesh from the small cube and modify the data related to "Bounding" for past with the "shape of the ship" ( else other ship will be able to fly trough your model since the bounding will be related to the very small cube )... for shield mesh, you need to use something like the a simplified "shape of the ship" a little scaled up...
This game is maybe 3 year old but the engine is very good... there is plenty of thing possible visually, some of them already implemented in some mod, some not yet used elsewhere, some not yet discover...
Below, some sample how some special effect can look ingame :
Original Omega from B5 mod... the center part is rotating
The texture on the central part is moving following a wave effect who move from the front to the back... only the texture move, not the mesh...
Transparency effect apply to the central section... for the light emitting effect ( with moving texture ), i have already show the Vorlon ship... pretty sure that some other effect are possible but i have no time so seek and test them... not sure that it is possible to make them via the particle forge since i have only use the notepad for edit/modify existing particle effect from the B5 mod, mainly the rotating effect... never tested it but if the game allow us to create our own fx code ( shader code ), there is plenty of other effect possible...