SolVanderlyn
Thanos acquires the fully powered Infinity Gauntlet in The Avengers: Infinity War, but loses when all the superheroes team up together to stop him.
Tidus' water weapon works extremely well within its game's thematic focus, has a visually distinct identity, remains useful throughout a good 85% of the game, has narrative relevance in being an heirloom from Wakka's deceased brother, and is an iconic piece of imagery that, along with Tidus, has come to represent the game itself. The idea of a weapon that looks like liquid water is cool in itself, but the way that the design was pulled off went above and beyond in giving it a distinct face - the head of a dragon coming off of the hilt and the bubble shaped underside are what really make this blade unique. The most appealing part of all are the shining bubbles that you can see coursing throughout the interior of the sword. It has an almost tribal look to it - perfect for blending in with the perpetually underdeveloped world of Spira.
What's your favorite sword in a game? Why? Say what game it's from and who wields it, because not everyone has played every game.
There's going to be at least one guy who posts an image with no text or explanation, and I hope the thread calls you out and shames you for it. EDIT: Don't be a wiseass.