If I'm not mistaken, then yes. But sorry if I'm wrong.
I guess? Though I played only with Butcher's Axe, Demon's Catalyst and Moonlight Greatsword. Everything else was kinda weak for me (I'm a Royal Tea addict).
And I broke my game's balance by going to Chaos Dungeon too early.
You have a chance of finding Moonlight Greatsword there too if you dwell too deep. If your character is weak or you don't want to break balance, just don't fight with anyone, skip layers and bosses while checking every golden chest (beware of mimics). At some depth your chances of getting rare weapons will increase and it will be possible to get Moonlight sword from some golden chest.
Honestly... this weapon is not very good without crits and high attack and magic. So finding buff Royal Tea is recommended too (buffs/skills can be found by reading flying books in the Chaos Dungeon. Some of them are mimics).