(Latin: "arms of Christ"1)
Frequently occurring motif in mediaeval and renaissance pictorial art. In this symbolism, the instruments of Christ's torture and agony2 were symbolically transformed, by the Resurrection, from having been tools of Christ's degradation and suffering, to becoming symbols of the Redemption of mankind by Christ through His sacrifice on the Cross.
The arma Christi often appear in eschatological imagery - depictions of Doomsday - where they are often held by angels. They also appear in images of Christ's suffering and in depictions of the Trinity (where they appear as an attribute of the Son).
1 "Arms" both in the sense of "weapons" and "heraldic devices".
2 That is, lash, pillar, ladder, nails, crown of thorns, lance and cross.