The first Signature : The firey flames doesn't match to be Riku's Aura.Riku is the power of darkness and he has blue hair.Fire isn't his element that makes him strong.I can even see some white dots around him which destroys the environment around him.

His blue hair of his can't go with the Fire background.6.5/10

The Second Signature : Seraphim's work.Now there's something that matches the personality of Sora.With a little bit of lighting combining with the bluey coloured background what makes it a good signature.8/10