I found the Wintertouched feat in D&D 4e, which grants you combat advantage against foes that are weak to cold. I'm wondering though, is there a version that gives you combat advantage if a foe is weak against fire?
Wintertouched's exact phrasing is this:
I searched the Compendium's feats list for "combat advantage fire", and "vulnerable fire". There were only three results for each and they weren't Fire versions of Wintertouched.
Since a Fire version isn't in the Compendium, which is a comprehensive database of almost* everything rules-wise in D&D, it probably doesn't exist.
You could make one up, though!
* To my knowledge the only thing they didn't document thoroughly was the Red Box player's book. It's safe to assume it contains basically everything else.