Today is the feast of Our Lady of Sorrows. One of the traditional depictions of Mary as Our Lady of Sorrows shows a sword piercing her heart. This comes from the prophesy of Simeon, "And your own soul, a sword shall pierce." (Luke 2:35)
Here is the first movement of Pergolesi's version of Stabat Mater Dolorosa. Here is the Latin:
Stabat mater dolorosa
Juxta crucem lacrimosa,
Dum pendebat Filius.
And the English:
The grieving Mother stood weeping
beside the cross where her Son was hanging