The concept of the edge is/was cool in theory, but never really worked right in practice. In short, the edge essentially allowed a character to pass a blindness check when they otherwise wouldn't have. Unfortunately, there is a really long list of things in CF that really don't like whether a character is blind within the scope of a single context (one action, one skill, etc.) being nondeterministic (i.e., containing an element of randomness). For that reason, I kicked it to the curb as far more trouble than it's worth.