Board Thread:Questions and Answers/@comment-34681548-20180213052442/@comment-1429792-20180213124913

With the normal cero, there is nothing established in the story about the colour being related to anything. I think its just a matter of making the characters more distinctive, adding a little something to what is a pretty basic and bland attack that many characters have. Then of course there are the Cero Oscuras etc that are different versions of the technique so warrant a different colour to make them more distinct.