Weapons in Call of Duty: Black Ops Cold War generally require you to break your back in multiplayer to unlock them. You will need to complete difficult challenges to unlock weapons from previous seasons, or to get new weapons that developer Treyarch adds mid-season.
Fortunately, for those who prefer Zombies over traditional PvP multiplayer, all of these weapons now have their own separate unlock challenges specifically for Zombies mode. After unlocking these weapons, you can use them for Zombies, multiplayer, or Warzone.
Zombies Weapon Unlock Challenges
Groza assault rifle
Using an Assault Rifle, kill 250 enemies who are stunned by your Stun Grenade or Dead Wire.
Using SMGs, Eliminate 1000 enemies while you have 5 or more Perks active.
Using Shotguns, kill 10 enemies rapidly 50 times.
Sledgehammer melee weapon
Using a Melee weapon that has been Pack-A-Punched three times, kill 250 enemies.
Wakizashi melee weapon
Using a Melee weapon, kill 150 enemies who are distracted by your Decoy or Monkey Bomb.
FARA 83 assault rifle
Using Assault Rifles, kill 30 or more enemies consecutively without getting hit 25 times.
Using SMGs, kill 250 enemies that are on fire.
Machete melee weapon
Using a Melee weapon, kill 200 enemies while shrouded with Aether Shroud.
E-Tool melee weapon
Using a Melee weapon, kill 50 Special enemies.
R1 Shadowhunter crossbow
Using a Special weapon that has been Pack-a-Punched at least twice, kill 50 Special enemies.
ZRG 20mm sniper rifle
Using Sniper Rifles, kill 50 Manglers after destroying their arm cannons.
Ballistic Knife melee weapon
Kill 300 enemies while you are using a Special or Melee weapon that is Epic or Legendary quality.