As Matt Cavotta referred to in his interview, each Battlemage from Planeshift contains two parts of the Coalition symbol in its artwork, corresponding to the two kicker colors each card has.
The five Battlemages are shown below (clockwise from top-left: Thornscape Battlemage, Sunscape Battlemage, Stormscape Battlemage, Nightscape Battlemage, and Thunderscape Battlemage) with the Coalition symbols highlighted. Check your other kicker cards for Coalition symbols, too!
Notice the "black" Coalition symbol on the Thunderscape Battlemage's axe. Sure, it's black, but that's really the blue symbol. Sometimes the artists make small mistakes -- so small that no one catches them until the card is printed.