Weapons need to be created on a clean way for the Technical animators so that there are no issues with the main mesh or geometry for faster moving over in the pipeline. For testing it would make sense to export the geometry to the engine to test the scale or the materials before handing it over for rigging or animating.
The files for the first-person weapons and the third-person weapons should be kept separate. To identify the correct files, first person weapons should use the _fp suffix and the third-person weapons should use _tp (for example: Sniper_fp.max).
These parts are included in the Geometry and should be separate elements. The element can be easily skinned to the related bones in the hierarchy for animating pieces like magazine or attachments.
There are special naming conventions for specific features which can be set in the script of each first person weapon or asset. The weapon_term for example will be the spawn point of the bullet geometry or the muzzle flash effect.
The third person weapons need physics proxies, which need to be attached to the weapon and should also appear in the weapons material. That is important for beeing able to pick up or throw away weapons later on in the game.
The weapons needs to look down the positive y-axis. The local axis needs to have the z-axis pointing up (identical to the world axis). This is especially important because attachments will take the world axis as the rotation reference.
Always clean up your scene and your model. Do not leave any transformations or rotations on the model.