I love the idea you've had with replacing flames for icicle-type feathers. I've never seen that done before. :]
I've done a quick idea of what you might look at for adding light and depth to your piece.
(I used the creature pictures GuardianAngel1 posted on page 5)
*Has had too much free time on her hands today* XD
1) I've placed the animals into the picture. Note that I've used gaussian blur with a colour around them, (on a separate layer beneath). This is REALLY handy for making things look like they're glowing.
2) Add depth by making differences in size between things. Notice how the one on top looks further away - the easy trick of size adds depth pretty quickly. :]
3) I've used a gaussian blur (on a separate layer) around the lights on the dragon. They look pretty bright, so I thought they'd probably cast a bit more of a glow.
I've also added light on the dragon's body where it might be reflected off. I'm assuming your dragon has scales so the light would reflect quite well.
4) More of a tiny thing than anything - maybe you could make the picture a bit wider to the left? The dragon looks a little squashed. :3
NB - glows can be seen in water as there are many particles floating around in the water - it's like air - you see beams of light when strong sunlight is shown up by particles in the air, such as dust. :]
Sorry for the massive rant, and I hope this helps!