Dune has a take on this that the movie doesn't do a great job at explaining. But the shield is made to prevent high velocity projectiles and energy weapons. This way the shield can be hidden and fool enemies because the user is still able to interact with daily objects. Like you can eat while wearing the shield and since you'd have body guards it's much harder to get in and stab someone wearing a shield. The Apple version of Foundation has a similar shield but it is more sensitive. Dune's shield has obviously affected many subsequent works.