This page contains content on features that are no longer part of the current version of the mod.
Scavenging was a system in which certain evil mobs are able to pick up and equip Armour and Weapons that they do not normally have. All variations of the Mordor Orcs, Angmar Orcs, Gundabad Orcs, and Uruk-Hai, and the standard Dunlendings, were able to scavenge weapons and armor, and were considered scavenging mobs.
Scavenging was removed from the mod in Public Beta 21. This was due to two reasons: firstly, the advantage of being able to equip some units with vastly superior equipment this way was considered overpowered; and secondly, throwing a spear at a scavenging mob would not hurt it, but would instead cause the mob to equip the spear.
Replacing the equipment of hired units is most likely derived from this function, with all mobs being able to be re-equipped as opposed to just some evil mobs.
A Scavenging Mob is a mob that is able to scavenge items and weapons. This means that when you throw a piece of armor or a weapon to a mob that is able to scavenge, and if the weapon/piece of armor you gave it is superior to the one they are currently holding, they shall replace it for the superior one you threw them. For instance, if you throw a Dunlending a Mithril Sword, he shall equip it. Once a mob picks up a weapon/armour piece they shall be unable to despawn.
However, there are exceptions to scavenging. Scavenging mobs will never equip an item that is inferior to the one already in their hand (so don't try giving an Angmar Warrior a wooden sword.) If you give a mob a piece of armor, it cannot be taken back (unless you kill the mob that you gave it to.) There are other exceptions as well, such as being unable to give Spears to units, and being unable to replace bows/crossbows of archers.
When you kill a scavenging mob that has been given weapons/armor it shall drop all that has been given to it, along with it's standard drop. Scavenging Mobs that do not have any armor and/or weapons (such as Dunlendings and Gundabad Orc Chieftains) can be given virtually anything, including random items such as food, blocks, and minerals. Giving armour/weapons/random items to a Orc Chieftain, Trader or Bartender shall not affect trading with them in any way.