I am not familiar with fallout or how the engine works, but usually 3d models have separate textures to deal with how light behaves with it.
For example, the diffuse texture is the base colors. Other common textures maps include things like specular map for what parts are shiny in the light. Normal maps for how light is reflected depending on the angle, etc.
An emission map would show where light emits from, and I suppose in this case is a black and white texture, where the closer to white the more light emits, like a mask. In your screenshot 'emissive color #ffffff00' looks like a hex value for pure white, normally written #ffffff. The multiple could be the factor. For example 1.5 would be 50% more.
But I really don't know or have an experience with this engine or what Nifskope is or generally what you are asking.
I think you should try to focus on what you are asking, and you will probably get a better answer.
edit--The vanilla glow texture has no transparency. Your version does. Maybe that is the problem. Maybe instead of a 32 bit image is should be 24. Also, it might should even be a 8 bit black and white. Think of the glow texture as a mask. The white areas are where the light comes from, and if follows the same UV coordinates as the diffuse texture. And the setting #ffffff00 is the color of the light.
For example, the diffuse texture is the base colors. Other common textures maps include things like specular map for what parts are shiny in the light. Normal maps for how light is reflected depending on the angle, etc.
An emission map would show where light emits from, and I suppose in this case is a black and white texture, where the closer to white the more light emits, like a mask. In your screenshot 'emissive color #ffffff00' looks like a hex value for pure white, normally written #ffffff. The multiple could be the factor. For example 1.5 would be 50% more.
But I really don't know or have an experience with this engine or what Nifskope is or generally what you are asking.
I think you should try to focus on what you are asking, and you will probably get a better answer.
edit--The vanilla glow texture has no transparency. Your version does. Maybe that is the problem. Maybe instead of a 32 bit image is should be 24. Also, it might should even be a 8 bit black and white. Think of the glow texture as a mask. The white areas are where the light comes from, and if follows the same UV coordinates as the diffuse texture. And the setting #ffffff00 is the color of the light.