A nuclear radiation rifle emitting an invisible beam of energy that can penetrate walls and vehicle. The victim would die shortly after from the incredible dosage of radiation poisoning, a quiet but cumbersome assassination weapon.
Hellvetica deployable riot shield
A repair drone from a bygone era when man still ruled the Earth. These machines' sole purpose is to maintain their subjects, the newly sentient 3 meter Amsumo war droids now worshipped by tribal men as a living god.
Revenant Cap, a helmet capable of storing memories and thoughts. A separate user can easily understand ideas, plans and strategies stored in by the previous person.
Sun discs, ancient devices used for accessing old bunkers and navigation