Rule of the Day 04/05/2011
pg 69 BRB - Flaming Attacks
Unless otherwise stated, a model with this special rule has both Flaming shooting and close combat attacks (though any spells cast by the model are unaffected, as are any attacks made with magic weapons they might be wielding).
In short, the only way that attacks from magical weapons will be flaming is if the weapon has the Flaming rule itself.
That character with the Fencers Blades in a unit with the Banner of Eternal Flame will not count as having Flaming Attacks.
Tactical Uses - Only a few I can think of though there are likely others...
Put a Char. in a unit with the Flaming Banner across from Dragon Princes. Dragon Princes charge think they can't be hurt and the character proceeds to whoop up on them. This also works vs. Characters with the Dragonhelm or Dragonbane gem.