The cyclone spear was a long, spear-like weapon that served as Iruini's Toa tool when he was a Toa Hagah.1, 2, 3, 4, 5 Iruini used it to channel and focus his elemental power of air. As an additional ability6, it could create massive windstorms strong enough to sweep away hundreds of foes at a time. Using the spear this way weakened Iruini, so he did so sparingly.3
Iruini presumably acquired the cyclone spear when he became employed as one of Teridax's Toa Hagah7 (all Toa Hagah were equipped with similar spears8). When Iruini was mutated by Roodaka into a Rahaga, the cyclone spear was mutated into a small staff.9 When Roodaka reversed Iruini's mutation, the cyclone spear returned to its original form.CN Iruini presumably continued to use the cyclone spear on Spherus Magna.