In the episode "Sokka's Master", we see him creating his own sword from the meteor. The episode's Goofs said that when plunged into the water to be cooled, the sword has a triangular end, but then when completely finished, it doesn't.
When I watched this episode, I looked many times for the sword to not have a triangular end, but all its close-ups (when you can tell) do show a triangular end. Even when Piandao first pulls Sokka's new sword out from its sheath, it has a triangular end.
Which scene (close enough that you can tell) does it not have a triangular end?