User blog comment:Dragoon leGreat/Gauis and Gwen- 5x12/13/@comment-5674726-20121128140521

I'd say that, if the finale ends up focusing on the battle, Gaius and Guinevere will have a very limited role. Short of Gaius coming along as a medic, which seems unlikely, he's not going to be part of the battle. It also seems unlikely that Guinevere would fight since her fighting abilities are limited, and since it's likely that they wouldn't want to have both King and Queen in the line of fire.

Short of one or both being killed as Berserk Buttons for Arthur and/or Merlin, their role could end up being mostly moral support before the battle.