Weapons on a Rampage is an Odd Job in Chapter 8, "Budding Bodyguard", in Final Fantasy VII Remake taking place in the Sector 5 Slums. Cloud Strife and Aerith Gainsborough talk to a scared man who has seen Shinra weapons in the scrapyard.
After talking with the scared man in the northern end of the Sector 5 Slums Center District, head north and right to Nuts 'n' Bolts Hills. If "The Mysterious Moogle Merchant" was completed and the graveyard key was purchased from Moggie, a door on the right along the way can be unlocked to use a bench and fully heal Cloud and Aerith's HP and MP. Proceeding further north in Nuts 'n' Bolts Hills finds the enemy. Head north and use a ladder to go up, then continue to chase north and use the path to the right to Scrapyard Back Alley to find Mark II Monodrives. To prepare, the Wind Materia is useful on both characters, especially if paired with Elemental Materia on Cloud.
Mark II Monodrives are fairly durable, and can block physical attacks when surrounded by a gray barrier or become immune temporarily to magic when surrounded by a green barrier. Against the gray barrier, Aerith should use her normal attacks, spells, or abilities to destroy their shield, before Cloud attacks under Punisher Mode. When the enemy is immune to magic damage, using Cloud is the only option, and should chase them down in Operator Mode and use normal abilities.
After the first batch of Mark II Monodrives are defeated, more are found in the wide area of Twilight Valley, northeast from the previous spot. Once they are defeated, the player can teleport back to the scared man to complete the quest. He will give the two a pair of protective boots, and open up the next sidequest, "Paying Respects".
Hard mode tips
The Mark II Monodrives are more durable than before, although many tactics against them are the same. Cloud can use Triple Slash to chase them down, but should only use this while none have a gray barrier protecting them from physical damage. Aerith can make use of Soul Drain effectively, which deals greater damage at higher levels with a higher Magic; this will not only deal magic damage to the Monodrives, but heal her MP. Casting spells is unnecessary for this quest, and should be avoided.
Completing the quest will give Aerith the Telluric Scriptures Vol. V.