I'll go with a little more helpful comments on this.
First, both of the sigs have a little too much contrast in the darker, and brighter parts of them. Even if you were aiming for a contrast, you should blend it in more and not make it so out of nowhere brightness.
Next, for fonts, the first one, I don't see any, which I think was what you did, but for the second sig, you can barely see it. A better color and blending could have helped. Make sure to match the style of your font with the sig too
Lastly, you should try out some blending a little more for the actual renders. Blending always balances a sig out. And I would recomend borders on those
Hopefully, this helped.