The following can be unlocked by obtaining the respective ranks listed

Weapons
Crossbow: Rank 10
Elephant Gun: Rank 18
Grenade Launcher: Rank 06
Machine Gun: Rank 2
Nail Gun: Rank 14
Pistol/Shotgun: Rank 1

Upgrades
Crossbow Damage Increase: Rank 21
Crossbow Rate of Fire: Rank 35
Elephant Gun Damage Increase: Rank 39
Elephant Gun Sniper Scope: Rank 25
Grenade Launcher Homing Grenades: Rank 17
Grenade Launcher Velocity Boost: Rank 33
Machine Gun Kickback Reduction: Rank 31
Machine Gun Magazine Size: Rank 13
Nail Gun Damage Increase: Rank 37
Nail Gun Magazine Size: Rank 23
Pistol Automatic Firing: Rank 5
Pistol Damage Upgrade: Rank 27
Shotgun Automatic Reload: Rank 29
Shotgun Rate of Fire: Rank 9
Speedy Hacker: Rank 24

Masks
Eagle/Tragic Comedy: Rank 10
Moon/Indigo Feather: Rank 20
Octopus/Demon: Rank 40
Peacock Feather/Sun God: Rank 30
Rabbit/Goat/Pink Feather: Rank 1

Melee
Crowbar/Flashlight: Rank 30
Hatchet: Rank 40
Machete/Rolling Pin: Rank 10
Mallet/Barbed Wire: Rank 20
Wrench/Candle Stick/Pipe: Rank 1

Plasmid
Air Dash: Rank 4
Electro Bol/Winter Blast/Incinerate: Rank 1
Geyser Trap: Rank 8
Houdini Rank: 16
Insect Swarm: Rank 20
Telekinesis: Rank 12

Tonic
Back Stabber: Rank 11
Big Game Hunter: Rank 36
Deadly Machine: Rank 32
Death Trap: Rank 38
Expert Researcher/Security Evasion: Rank 3
Fast Feet: Rank 30
Headhunter: Rank 34
Leg Up: Rank 28
Metabolic Eve: Rank 15
Repairman: Rank 22
Resurrection: Rank 40
Sabotage: Rank 19
Slugger: Rank 26
Speedy Recovery/Eve Saver: Rank 7