The khanda is a straight double-edged sword, and though it is a weapon in form its central religious use is not martial but sacramental: it is the implement that prepares the water of Sikh initiation.
Stirring the amrit
At the Amrit Sanchar, the Sikh rite of initiation into the Khalsa, sweetened water is stirred with a khanda while the scriptures are recited, and this stirred water, the amrit, is then given to the initiates to drink and is sprinkled on them. The double-edged sword is thus the instrument by which the initiation is effected, and its use in this way gives the object a significance far beyond that of a weapon. The same word names the composite emblem of Sikhism, in which a central double-edged sword is flanked by two curved swords and encircled by a ring.
Sovereignty and the two swords
The double-edged sword in the emblem stands for divine knowledge that cuts through illusion, the ring for the oneness and eternity of God, and the two flanking swords for the twin authority, spiritual and temporal, that the tradition holds together, so the khanda gathers the central ideas of Sikhism into a single sign. As a weapon it belongs to the martial dimension the tradition took on under the later Gurus, but its defining religious act is the stirring of the amrit, which places a sword at the very centre of the rite that makes a Sikh a member of the Khalsa.