The sword that Minako has, where is that suspposed to be from?

Only in the manga. "A sword found by the senshi on the moon in Act 10, Volume 03. It was stuck into the ground, and Sailor Venus was the only one who could free it. It is a stone sword upon which the way to seal away Queen Metallia is inscribed. Sailor Venus uses it to kill Queen Beryl, and Sailor Moon uses it to kill herself and Mamoru." - from 'The Oracle :: BSSM Encyclopedia'

See also http://www.wikimoon.org/index.php?title=Sword_of_the_Silver_Crystal