Fuel Rod Cannon Kill
From Halopedia, the Halo wiki
Fuel Rod Cannon Kill is a medal awarded in Halo 4 multiplayer and Spartan Ops for killing an enemy with the Fuel Rod Gun. The player will also be awarded the medal if an AI passenger in a vehicle they are driving kills an enemy with the fuel rod gun. It is represented by a fuel rod in flight on a blue circle atop a grey four-pointed star.