The twin cutter1, 2, 3, 4, 5, 6, also called the twin cutters7, 8, was a two-pronged, claw-like weapon that served as Matoro's Toa tool when he was a Toa Mahri. Matoro used it to channel and focus his elemental power of ice. It allowed Matoro to fire twin blasts of ice and was specially made to withstand super-cold temperatures.4
Matoro acquired the twin cutter when he was transformed by the Mask of Life from a Toa Inika into a Toa Mahri. Presumably, his former energized ice sword was transformed into the twin cutter. It was presumably destroyed along with the rest of Matoro's body when Matoro used the Mask of Life in Karda Nui.