I don't know what you guys mean by the render doesn't fit well. If you're talking about the colours I think the colour of the render doesn't always have to match that of the BG.

The way you've softly colourized the outside of the render in an electric blue colour is awesome. You've made it look somewhat like the knight is entering the atmosphere, the bright green lights accensuate this further. Also, the vivid, bright brushing towards the left just adds to this, overall creating depth and a scenario. I think the typography and text effect works nicely with the knight theme, also.

I really like this signature, you've done good man. Only one tiny single thing I don't like about this is the white cloud hovering to the right of the knight's head.

In short, it's a great sig. Very good job.