In this piece, the woman (saint) holds a stone which was used to punish sinners in Biblical times.
In her left hand, she holds a tulip which is a symbol for love. The arm which holds the tulip is incomplete. Our natural inclination as humans is to judge first and love later. Christ asks us to love first. Loving someone first goes against our human nature, so it is a process which is implied by her unfinished arm. In one of my favorite encounters with Christ He advises, “If any one of you is without sin, let him be the first to throw a stone…”(John 8:7). In the same story, the eldest of the group left first.