Holy crap, thank you so much. That must've taken a while to type up xD 

That is fantastic advice, and should solve the issues. I don't know why I thought contrast would be high on the glowing object itself... but again, thank you so much. I'll try working on it later today when I get some artistic time :D

Staggered gradients and dithering on that big halo are the easy ways, though perhaps mutually exclusive with each other. But, you can make things glow witohut using any kind of halo effect by careful use of colours., enhanced perhaps by a subtle halo in the form of a 1-2px outline.

Some tips to create glow without halos:

- Make the glowing object overall brighter than its surroundings. This means both lighter in value and more saturated. This isn't a encessary step but it helps a lot and can even do the job on its own!
- Use hues that contrast. If the background is cool, the glow should be warm, and vice versa. In your scene, neither background nor Navi have a strong hue identity, which is hurting your glow.
- Reduce the overall level of contrast in the glowing object, unless some parts aren't glowing. The reason for this is if something is glowing, it will look slightly overexposed compared to the normal environment. Alternatively, when the glowing object is the focus (which it isn't here), you can go the opposite route and reduce the contrast in and darken the background instead.
- If you can, darken the background in the vicinity of the glowing object, but not overall. This makes the glow feel stronger, creating an HDR-like effect. Don't add a gradient or a circular area of darker colours, because that'll look weird. Instead, use more subtle tricks, like having what looks like a shadow spot in the rocks behind Navi.
- Optionally, make a "gradient" inside the character. Put their lightest colour in the center, and their darker colours towards the edge. But, keep them saturated.

To help reinforce the glowiness, you could add highlights in the rest of the scene where other objects are reflecting the glowing light. Be careful with those, use thwem sparingly or the scene will look weirdly lit, and make sure the direction is consistent with them being from the glowing object.

Examples (non-pixel art because it's easier to search NPA):
[1] - notice how the girl, especially her shoulder and chest appear to glow even though there's no halo. Notice how that area lacks a clear distinction between the skin and the dress, this reinforces the brightness. Also notice that the dress uses about the same colour at the bottom of it, but it doesn't appear to be glowing there; that's because the background is lighter there. The hair also appears to glow a little bit because it's more satured and lower-contrast than ither things in the scene.
[2] [3] - These uses the last tip with making a gradient inside the glowing object, but also notice the lower level of contrast within the glowy areas, and the use of saturated colours that contrast with the ambient colours of their surroundings.
[4] - This one uses the internal gradient in the foreground jar, but not the background jars, where it relies solely on saturation, hue contrast, and reflections.

With how long it took me ti find these, I probably should've just done a draw-over for you :'D When you look for reference of how to do this, don't look up glow, because the people who really want to show off their glow (by tagging it/talking about it) are usually the ones who do it poorly xP