a) Class
Soldier, Vanguard, Infiltrator, Engineer, Adept, Sentinel

b) Weapon upgrade
Upgraded primary weapon, Shotgun, Assault rifle, Sniper rifle

c) Loyalty skill
1) Slam – lifts a target and slams them to the ground, inflicting damage

2) Barrier – surrounds the user with a high-gravity mass effect field essentially strengthening the player’s shields for a certain period of time

3) Energy Drain – drains enemies’ kinetic barrier power to boost your shields

4) Armor Piercing Ammo – does extra damage against armor and enemies with no defenses

5) Shredder Ammo – tears through soft targets, inflicting more damage to unshielded organic enemies

6) Dominate – can brainwash an organic enemy, forcing him/her to attack his allies. It works the same as AI Hacking but on an organic target.

7) Fortification – reinforces armor with a non-Newtonian fluid that hardens when struck, providing a brief, huge bonus.

Warp Ammo – effective against barriers and health, and does increased damage against enemies who are being affected by biotic powers.

9) Neural Shock – cripples organic enemies.

10) Reave – biotically attack an opponent’s nervous or synthetic system, disabling any health regeneration the target may possess, as well as dealing damage over time

11) Geth Shield Boost – improved geth shield technology able to deflect attack damage.

12) Inferno Grenade – launches a volatile grenade that explodes on impact, sending fragments flying in all directions that causes extra damage. This fire damage is effective against armor.

viaBest class + weapon + loyalty skill combo – Mass Effect 2 Message Board for Xbox 360 – GameFAQs.