Weaponoids
The weaponoid is a large generally humanoid shaped robot that is functionally a walking weapon. This isn't to mean that they are capable of deploying themselves, but rather, should they adopt their weapon stance, something else suitably large could pick them up and use them as a weapon.
The Urban Protocols and limitations on paramilitary and security mecha meant that in times of military crisis, many available mecha were unarmed or drastically under-armed. A potential answer for this was floated in the idea of the weaponoid. The prototype weaponoid was a self mobile version of the Wolverine's autocannon. Most of the weaponoid's mass consisted of the gun components, but it could stand and move on it's own. The addition of a humanoid chassis, internal power system, and other components increased the effective weight of the weapon system, but not to a degree more than something like a Wolverine main battle mech or Sentinel security mech couldn't handle.
The original weaponoids were a backburner project that was an attempt to recreate self propelled guns that weren't covered by the anti-tank bans. Replacing tracks with legs, and turrets with arms, the designers made bizarre insect like walking cannons and crawling missile batteries. The machines had two modes, an active mobility mode, and a fixed firing mode. When on the move, the weapon system was typically unavailable. Barrels were segmented, housings were locked down in armor modes, there wasn't enough power to spare for locomotion and firing solutions, and so forth. These programs ultimately failed as powered armor troopers handled the jobs better, and the self propelled systems were prone to breaking down, were often slow, and when moving, very easy to engage and destroy.
The Adventures of CannonMan was a military propaganda adventure series that followed a sentient auton who had the ability to turn himself into a giant cannon. He couldn't shoot himself, and had to be picked up by a robot to keep in the fight. The series was fundamentally identical to the Lone Ranger, with CannonMan being the Lone Ranger, and Turret the giant unarmed mecha was Tonto.
Practical Application
Weaponoids have not successfully been deployed, and currently are nothing more than a weird military project. The desire to have a robot that can run up to a mech and transform into a weapon have been stymied by the fact that the comparable robocized version of a weapon is often twice as heavy as the regular weapon, and much more prone to fouling or being damaged.
Weapon Droids
Weapon Droids have proven successful, if much less dramatic. A weapon droid is an unmanned kaze type aerial vehicle. Working either solo or in groups of up to eight, these rather small drones have proven able to airlift self contained weapon systems and deliver them to mecha and robot units in the field. While much less incredible, the droids are not performing a new function, as the droids are simply running logistic support flights carrying arms rather than ammunition. The droids are also rather vulnerable to hostile fire and are easily destroyed, requiring either escort, good luck, or a clear corridor of operations. The military has used droids in this capacity for years, moving power armor troopers, supplies, gear for mecha, and even field construction equipment, with little fanfare. The Sikorsky 'Skylord' Kaze can lift a Wolverine by itself. It isn't a popular military use droid as it is large and easily engaged and destroyed. In such hostile areas, the military favors carry-all transports.