Close Call
From Halopedia, the Halo wiki
Close Call is a multiplayer medal in Halo: Reach. It is awarded when a player kills an opponent when they themselves have no shields. The player receives the medal when their shields begin to recharge, signifying that they have survived the encounter.
In the Halo: Reach Beta it was awarded when a player killed an opponent when he/she had no shields and had one health bar. Most players died once this medal has been received as the player was extremely vulnerable to enemy fire once it had been acquired. In the Halo Reach Beta, the announcer verbally announced the medal but does not in the final game.