A Shield is a type of personal armor used to block attacks. They are commonly carried by Heavy Sentries. They are also deployed by some ICPs in the non-canon game TRON 2.0.
While this is a less known weapon it is a versatile weapon. In the series TRON: Uprising, system moderators such as Tron and his team often employ shields when acting as riot guards.
In TRON 2.0, shields are static objects and remain persistent until the program holding them is derezzed. Shielded ICPs rezz in with these shields. On the other hand, in TRON: Uprising, shields can be rezzed or derezzed at will, depending on the program. There appears to be no apparatus for the shield, and therefore must be part of the program's code. These shields can be derezzed from contact with disks, but have been proven to be capable of withstanding several hits.