What? I used the dimensions of your sig for my current one and it's cut off at the bottom.
The first one is to much of one color. It's all shades of grey in other words. And I don't think it looks good. :/
That's not really constructive criticism, I asked how I could improve it. Maybe add a bit of small blue details? Or what? To be fair, the main aspect is black. 
Honestly that one was my favorite, the other's are too gaudy to me. I'm more of a LOTR kind of person than a Warhammer type. I prefer subtlety. I also prefer silver over gold. So if that's not your preference, I'd rather you make your words reflect that a bit more. Saying you don't think it looks good is different than it not fitting your taste. So is it just taste? Or does the tex actually look bad in your opinion? 
That said, the third is only 2 colours really, and the second is only really 3. There are more one tone shields in existence than anything else historically speaking. It's a shield, not an accessory. 
Other than that, is the metal texture too scratchy?
Edit: Does this look better Dragon, or nah? I haven't touched the mesh yet, just worked on the tex based on your suggestions. Ignore the difference in metal, that's because the new one doesn't have a spec map yet.
New Comparison