A Sword is a metal weapon that comes in different forms. Swords are often long and carried in a hand or two hands. Different cultures in the Milky Way and Pegasus galaxy developed swords. Satedans used the sword of the Satedan Planetary Forces to fight Wraith. (SGA: "Broken Ties")
The deascended Merlin placed a sword in "Avalon" as a test to be able to defeat a black knight, which was accomplished by Cameron Mitchell when Stargate Command discovered the place thanks to Vala Mal Doran. Another such Sword in the stone was placed on the planet Camelot which again was the only weapon capable to defeat the black knight placed there to protect Merlin's library. (SG1: "Avalon, Part 1", "Camelot")