The Instruments of the Passion: the cross, nails, crown of thorns, lance, sponge, column, and other objects associated with Christ's suffering.
Arma Christi are the Instruments of the Passion: objects associated with Christ’s arrest, torture, Crucifixion, and death. Typical examples include the cross, crown of thorns, nails, lance, sponge, column of the Flagellation, hammer, pincers, ladder, dice, and the inscription INRI.
Etymology
Latin arma Christi, “the arms” or “weapons of Christ.”
Sculptor Notes
In sculpture the Arma Christi can form a compact symbolic program on shields, tombs, predellas, altar fronts, reliquaries, or relief panels. Their effectiveness depends on clear silhouette and hierarchy; too many small attributes at equal scale become visual noise.
References
https://www.metmuseum.org/art/collection/search/475525; https://www.metmuseum.org/essays/the-crucifixion-and-passion-of-christ-in-italian-painting