Some excellent commentary here on investment edge from John Huber (portfolio manager at Saber Capital Management, LLC).
http://basehitinvesting.com/what-is-your-edge/
A quick follow-up...
It seems to me that time and temperament are the two main investment edges available to individual investors. Individuals can be long-term oriented in their investments (they don't need to show short-term performance to keep clients happy), and they can patiently wait for the right pitch to swing at.
On the other hand, informational and analytical edges can be difficult to achieve and maintain. There are a lot of smart people running around out there, and some of them probably have better information and a better understanding of what's going on.
So, I think it pays to be humble regarding what you know and only invest when the odds are heavily in your favor.