The Soldier is the only class that has the advantage of upgrading the four types of weapons in the game: pistols, rifles, snipers, and shotguns. Upgrading means the player can improve each of the weapons talents. Your weapon talents are abilities that increase power and accuracy percentages, doing more damage against enemy shields and armor. Each weapon type has twelve levels of improvement. If you improve from the first level to the second and so on for the pistols, for example, it means that the pistol-type weapons you find or buy in the game will be much stronger. Other classes are limited to one or two weapons they can level up. For instance, the Vanguard can only increase the abilities of the pistols and shotguns.
Only the Soldier can upgrade all four types, and therefore only he can unlock each of the four weapon types' special abilities, such as Carnage for the shotguns and Assassination for the snipers. These special abilities bring additional perks like heavy damage, heat reduction, and longer fire rate. They will be especially useful once you get into the thick of combat against a crowd of enemies, especially the battles where you encounter Geths and Krogans at the same time. Players who think of themselves as pure shooters should be satisfied with the Soldier class because of its emphasis on combat and the wide selection of weapons
In the beginning the Soldier can only upgrade the talents of the pistols and the assault rifles. If you continue to improve your pistols' talents you will unlock the shotgun; upgrading the assault rifles will unlock sniper rifles. Leveling up the assault rifles should be a priority for the Soldier since it does a better job of spreading firepower against a group of enemies than the pistols, shotgun, and snipers. In the game your enemies tend to attack in groups, sometimes they will rush at you recklessly or use strategies like flanking. Those are the moments when the assault rifles will come in handy.
Besides being able to upgrade the four types of weapons in the game, the Soldier class also has a solid defense with his armor and shield talents. The Shield Boost ability restores some of the shield that is lost in combat. If all your shields have been wiped out, the next best option may be to go with Immunity, an ability that will help the Soldier take less damage from enemy fire. Other than your teammate, the Krogan Battlemaster named Wrex, the Soldier is the only class who can wear heavy armor.
The advantage of heavy armor means you will have the best defense against enemy fire, as long as you can buy or find the best heavy armors out there. If you have the best heavy armors, you can count on longer lasting shields and better protection from those annoying enemies that try to reduce your shields, freeze your weapons, or throw you across the room. Heavy armors will be a nice luxury when you face Saren, Krogans, and mini-bosses in the side quests. These support talents and heavy armors available to the Soldier class arealready a solid foundation to a good defense, but later on there are additional opportunities to increase health and regeneration as well making you able to really soak up attacks.