Players can craft an Adventurer's Satchel using the Tailoring skill under the Utility Items category
Adventurer's Satchels are Blessed and can only contain other Blessed Items (such as Codexes, Poison Kits, Blessed utility/deco items, etc)
Players can shift-click an Adventurer's Satchel that they are carrying and select "Add All in Backpack" to move all Blessed items from their Backpack into the Adventurer's Satchel
Liftlock
Adventurer's Satchels have a "Liftlock" mechanic that players can toggle to prevent them from being Lifted while inside their Backpack
Players can shift-click the satchel (while inside their Backpack) and select "Enable Liftlock" to enable the feature or select "Disable Liftlock" to disable it
While Enabled, if a player tries to Lift the item from their Backpack, they will be prevented from doing so and receive a system message informing them as such