That’s not really a vorpX issue but related to how many first person games handle weapon rendering. To look good on a monitor often weapons are rendered as a separate layer with different projection settings (read: lower FOV for the sake of simplicity) than the game world.
That’s not true for all games, but I’d say about 2/3 or so handle it that way. If Geometry 3D is supported for a game, you can get around that by using the ‘Camera Height Modifier’ option in the vorpX menu (under ‘More 3D Settings’ to lower the weapon a bit. A little height offset can do wonders.
BTW: In Geometry 3D games typically 1.0 is the correct value for natural world scale, at least as far as official profiles are concerned. Base G3D parameters are usually dialed in during authoring to ensure that. Might not always be 100% perfect, but at 2.0 the world will typically be too small. For Z3D things are a bit different. 2.0 is usually a good value for correct scale at medium to far distances where you look at most of the time while actually playing a game.