In the BioShock 2 Multiplayer, the player gradually builds up an arsenal of powerful weapons. Two of them are available from the start, while the rest are progressively unlocked as the player progresses through the Ranks. They are wielded simultaneously with Plasmids, and can be upgraded after reaching a certain level. Players will have different melee weapons depending on the character chosen, the difference being purely cosmetic. As the player advances through the ranks, they will be able to widen this selection. These weapons can be upgraded, but only one upgrade can be fitted at a time to the weapon. Also, unlike in the main game, these upgrades also reduce one of the weapons' other characteristics (for example, the Crossbow's Piercing Shot Upgrade allows bolts to pierce through enemies, but also increases reload time).
Unlocked from the start, the Pistol is the most versatile weapon in the game, capable of landing moderately damaging shots with precision. In addition to a fairly large cylinder capacity, it also has a high rate of fire and the shortest reload time of all the player's arsenal. Although this weapon is useful in most situations and can help the player determine their playstyle, it doesn't excel in any particular form of combat compared to other more specialized weapons. As the player progresses, they will be able to upgrade the Pistol's damage and cylinder capacity size, and even render it fully automatic.
Also unlocked from the start of the game, the Shotgun is the most powerful close-range weapon in the player's arsenal. Each shot is capable of dealing a large amount of damage, and the weapon's spread means it does not require precision aiming to function properly. However, this power is mitigated by the weapon's short range, slow rate of fire and long reload time. Eventually, the player will be able to compensate for these flaws by upgrading the weapon's damage, rate of fire and reload time.
Unlocked at Rank 2, the Tommy Gun is a mid-range weapon capable of laying down continuous sustained fire. Its strength lies in its high rate of fire and relatively large magazine, allowing the player to tackle groups as well as individual enemies. On the other hand, its high recoil and general inaccuracy limit its effectiveness at longer ranges. Over time, the player will be able to upgrade this weapon's rate of fire and magazine size, and eventually reduce its recoil.
Unlocked at Rank 6, the Grenade Launcher functions as a strong mid-range burst-damage weapon. Its high splash damage allows the player to harm multiple enemies at a time as well as hit their targets more easily. On the downside, this weapon has a slow rate of fire, a small ,magazine, low ammo reserves, the longest reload time in the game and a risk of dealing self-damage if fired at too close ranges. As the player advances through the ranks they will be able to upgrade the weapon's magazine size and fire rate simultaneously, turn its Grenades into heat-seeking missiles and increase the speed of its projectiles.
Unlocked at Rank 10, the Crossbow is the first
true long-range weapon the player obtains. Its sniping capabilities are bolstered by its four-shot magazine and potent headshot damage bonus, while its slow rate of fire and projectile travel speed greatly limits its effectiveness in direct combat. Later on, the player will be able to give the weapon the ability to pierce multiple targets, higher damage or even a boosted fire rate.
Unlocked at Rank 14, the Nail Gun functions as a powerful mid- to close-range ambush weapon. Although it requires to be charged up before being able to fire, it possesses the highest rate of fire in the game, coupled with a large magazine and very little recoil. On the other hand, its wide spray prevents it from being used accurately. Towards the second half of the game, the player gains the option to make the weapon fire in precise bursts, increase its magazine size, or even augment its damage output.
Unlocked at Rank 18, the Elephant Gun is the final weapon received by the player. It is both precise and highly damaging, capable of felling an enemy in a single headshot. On the downside, it has an extremely small magazine, a long reload time, and is incapable of killing an enemy if one emptied the weapon's magazine into their body, making it extremely unwieldy in the hands of an inaccurrate player. Towards the end of the game, the player will be able to solve this problem by doubling the Elephant Gun's magazine size, adding a sniper scope for greater long-range capabilities or increasing the amount of damage dealt with every shot.