The Shikra blade was a melee weapon that was created by the Goa'uld Empire.
These swords had their edges honed to the thickness of a single atom making them extremely sharp to the point that a single slip was capable of cutting a Human body in half with apparent ease.
In an alternate timeline where the Stargate Program never existed, the Sovereign Ba'al took command of the Goa'uld empire. He made use of his personal Shikra blade to cut off the top of a defiant Apophis' head. Later, Qetesh stole the sword and used it to pierce Ba'al's body from behind in order to gain information on how he knew so much about the Humans of Earth. When she was satisfied that she had gained all the answers she needed, Qetesh split Ba'al's Human host in half, killing both the host and symbiote before throwing the sword away to kill Teal'c who had seen Ba'al's death. (SG1: "Continuum")