A player’s loadout can have up to 3 weapons; primary, secondary, and melee. It is not necessary to be equipped with one of each, though at least one weapon must be equipped.
Primary weapons are mainly separated into rifles, shotguns, sniper rifles, and bows, as these are the four categories that have unique mods to them, as well as Sortie missions limited to each type.
“Rifles” includes practically all primaries that aren’t separated into the other three categories; this includes fully automatic assault rifles, semi-automatic precision rifles, beam weapons, explosive launchers, and others. Most of them use Rifle ammo, though most launchers use Sniper ammo.
Shotguns have their own set of Mods and use the rarer shotgun ammo.
Sniper Rifles have magnifying scopes and the unique Shot Combo mechanic. They share mods with Rifles but use the rare Sniper ammo.
Bows, as well as crossbows, use Rifle mods. Bows use Sniper ammo, while crossbows use Rifle ammo.
Secondary weapons come in many forms, mostly pistols, though also throwing knives, shotguns, and launchers. They all use the same mods and Pistol ammo, however.
Melee weapons do not use ammo. They all use the same mods, though there’s a variety of melee types, each with their unique Stances.
Robotic weapons serve as weapons used by Sentinels and Moas. They have internal magazines that they must reload but do not require ammo to stock. Their mod types depend on the weapon equipped (e.g. Deconstructor uses melee mods, Artax uses rifle mods).
Certain Warframes come with Exalted Weapons that are tied to their abilities. These can be modded as with normal weapons, but do not require separate copies of the mods. These weapons don’t require ammo.
Kitguns and Zaws are modular primary, secondary, and melee weapons, respectively, assembled from a variety of parts. In addition to mods, they can be equipped with unique Arcane Enhancements.
How much damage is dealt with Health and Shields. Can consist of several damage types, either Physical or Elemental damage.
How tight of a spread a weapon has when firing. A weapon with 100.0 Accuracy will always hit on the center dot of the reticle, whereas a weapon with lower accuracy will see a larger spread over multiple shots.
How quickly the weapon is reloading.
A weapon with 1.5 Reload Speed means it takes 1.5 seconds to reload.
Amount of shots you can fire before you have to reload.
Charge Time/Heavy Wind Up Time
How quickly a weapon can be charged and damage it does from a charge.
Mainly bows, but also in effect for other weapons like the Opticor.
Heavy attacks for melee weapons have a wind-up time before an attack.
Critical Chance/Hit Multiplier
The chance that a weapon will land a critical hit and how much more damage it deals.
Orange critical hits deal increased critical damage and can be scored if the critical chance lies above 100%. Likewise, red Critical hits deal further increased critical damage if the Critical chance lies above 200%.
The chance that a weapon will land a proc depending on the damage types.
How quickly the weapon fires its ammunition. Semi-automatic weapons are highly affected by frame rate, resulting in fire rates at around half their depicted values.
Total amount of ammunition that can be carried (including magazine).
The range where a weapon deals less damage, up to a maximum distance.