From Halopedia, the Halo wiki
The Skewer is an anti-tank weapon employed by Banished Jiralhanae, with such operators known as "Skewer-bearers". The launcher fires a "rocket-sized" spike capable of piercing through the armor of a main battle tank, or punch through the energy shields and titanium shell of GEN3 MJOLNIR armor, even from range. The launcher has an emitter of some kind, likely of gravitic operation similar to other Jiralhanae spike weaponry, which is used to launch the spike round and can be intensified - presumably to adjust the muzzle velocity of the fired projectile.
When ready to fire, the Skewer's spike projectile in the barrel can be seen sticking out of the weapon; underneath the barrel is a sword-length bayonet. When used against infantry, the force of the projectile impact is enough to send the target flying back, or knock them off elevated surfaces. They can also be used as anti-air weapons, with the spikes capable of penetrating the armored cockpit of a Phantom dropship.
The Jiralhanae Choros wielded a Skewer during the raid on the keyship Anodyne Spirit during the Second Ark Conflict. Later, several Skewers were employed by Banished forces on Reach during Operation: WOLFE.
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