The Demon Sword Soul Crusher (once Ashram gets control over it, totally badass) – Record of Lodoss War
Tetsuiga (I love the way it can absorb demonic powers) – Inuyasha
Veritech Fighters, specifically Skull One – Robotech (yes Robotech not Macross, because that’s the version I grew up with)
ZGMF-X20A Strike Freedom Gundam (the definition of overpowered) – Gundam SEED Destiny
I probably could go on for longer, but I’m literally drawing further blanks…mind shutting down for the night, I guess :P