FINAL ROUND - The last round in a magazine deals bonus damage.
The last shot in your magazine deals 33% additional damage
In Destiny, FINAL ROUND is a Weapon Upgrade that can be found on nearly all Hand Cannons, Scout Rifles, Shotguns and Sniper Rifles in the game. Weapons in Destiny pull each Upgrade at random from specific pools (with a few Weapons that are an exception). This upgrade significantly increases the damage of the last round in your clip.
To see more info on exactly which Weapons this Upgrade can be found upon click the link below:
To see more about how this Weapon Upgrade fits into these pools, please click the links below:
HAND CANNON WEAPON UPGRADES
SCOUT RIFLE WEAPON UPGRADES
SHOTGUN WEAPON UPGRADES
SNIPER RIFLE WEAPON UPGRADES