User blog comment:Waterwecna/Diamond of the Day Part Two: Review/@comment-5465618-20121225005720/@comment-5674726-20121226114731

''But the scene with Gwaine and Percival going after Morgana was just stupid and useless. Gwaine being killed off -- I totally agree that his death was a waste and meaningless.''

It was the indirect cause of Morgana's death. Had Gwaine and Percival not run off to confront her, it would have made no difference to Arthur's fate, since he wasn't going to reach Avalon on time anyway. Morgana would have been off on a wild goose chase, Arthur would have died and Merlin would have chucked Excalibur into the lake.