Sorry, neither you Jump Off, nor you DB Pheonix are correct in what you say about an edge.
What you both describe is prudent trading, as a consequence of mechanical skill.
An edge is much more than that, because it involves possession of total expertise.
Total expertise does not just encapsulate very deep and detailed knowledge about all this, it includes having extra abilities that confer upon the holder that extra indefinable advantage.
This is because in addition to all the components being crucial to the core skills of a trader, there are other add ons, which are specific extras.It is these add ons that give the edge.