Shields are an ancient yet extremely useful adjunct to body armor. A force pavis is more effective, being a small pretech force disc projector that can absorb all manner of small arms fire. All shields require one free hand to use effectively.
Shields grant a base AC to their user; 15 for a force pavis. If the bearer’s AC is already equal or better, the shield simply grants a +1 AC bonus.
Aside from their AC benefit, a shield also renders the bearer immune to the first instance of melee Shock damage they take each round, assuming the shield is effective against the weapon being used.