Energy stave
From Halopedia, the Halo wiki
The Honor Guard Pike is a Covenant weapon.
It is a melee weapon used exclusivly by the Honor Guards. These weapons are long staves with a spear-like end that is similar in color to the "fins" of their weilders. Not much is known about these exotic weapons, however they have a lenght of 427.5 centimeters. They do not seem to have much of a combat purpose but more a ceremonial one, as the Honor Guard use Plasma Rifles and Energy Swords in real combat. However they were used by Brutes to kill any Grunts that came to close to the Council Chamber during one of the High Prophet of Truth's sermon regarding the discovery of the Sacred Icon.