I have gotten quite a bit of email from folks who don't grasp Edges. Not mechanically, but understanding what Edges are suppsed to represent. They are continually confused with Traits, which are fundamentally different, both mechanically and conceptually. Here's another try:
Who would you trust to guide you through an arctic blizzard - an guy from Point Barrow Alaska, or a guy from Vero Beach Florida? Why? Does the Alaskan have a skill called "Blizzarding?" Is there such a skill? Should there be such a skill?
I don't think it's a matter of skill at all - it's a matter of experience with a specific condition. The Floridian is very unlikely to have a lot of experience with snow storms. The Alaskan, on the other hand, probably has been through a few. They know what it's like, what dangers to avoid, what clothing to wear, what foods to eat. This is an Edge.
Edges can be a result of Repeated or Prolonged Exposure to that Condition, or of Intensive Training in that Condition. An example of a Training Edge is a US Navy SEAL. Intensive training drives home the value of Teamwork. SEALs always operate as members of a Team. A SEAL always operates with a "swim buddy" - the basic Seal unit is two, not one. In training, prospective SEALs are given tasks they can only perform as members of a team. Individualists are flushed out of the program. The Teamwork Edge is trained into them.
So - Edges are bonuses that are due to experience working while exposed to a Condition. When a Condition matches the Edge, that person has a bonus while that Condition is affecting things. If a character has the Snowstorm Edge and it is indeed snowing, but the characters are inside a heated, lit building, then the Condition is not affecting anything, and the character's Edge is not operating.
Hopefully, this explanation works! :D