In art, the "swords which pierced Mary's heart" represent:
at the prophecy of Simeon;
at the flight into Egypt;
having lost the Holy Child at Jerusalem;
meeting Jesus on his way to Calvary;
standing at the foot of the Cross;
Jesus being taken from the Cross;
at the burial of Christ.
There’s nothing scriptural to signify the Mary of the Bible was knifed seven times...that is your religions pretending and making up their own story to keep people entrapped with Mary Worship..... as they twist and distort everything that is of God.