Determining the "strongest" weapon in anime is subjective and depends on various factors such as the context, power system, and the specific anime series being considered. However, here are a few notable examples of powerful weapons in anime:

1. Excalibur (Fate Series): Excalibur, the legendary sword associated with King Arthur, is a prominent weapon in the Fate series. It is depicted as an incredibly powerful and sacred weapon capable of unleashing devastating magical attacks.
2. Death Note (Death Note): While not a physical weapon, the Death Note is a supernatural notebook that grants its wielder the power to kill anyone by simply writing their name in it. The Death Note's influence and consequences shape the plot of the series and make it a formidable tool.
3. Dragon Slayer (Fairy Tail): The Dragon Slayer magic in Fairy Tail grants certain characters the ability to slay dragons and absorb their powers. The weapons used by Dragon Slayers, such as Natsu Dragneel's fiery attacks, make them formidable combatants.
4. Gurren Lagann (Gurren Lagann): Gurren Lagann is a colossal mecha in the anime series of the same name. It has the ability to combine with other mechas and grows exponentially in size and power throughout the series, showcasing immense strength and firepower.
5. Bankai (Bleach): In the world of Bleach, Shinigami can unlock their Bankai, which grants them tremendous power and unique abilities. Bankai releases manifest as different weapons or forms, such as swords, armor, or energy constructs, depending on the character.

These are just a few examples, and the concept of the "strongest" weapon can vary greatly depending on the anime series and its specific lore, power systems, and storytelling. Different anime may feature their own iconic and powerful weapons that captivate viewers and contribute to the series' overall narrative and action sequences.