Type-10 Energy Weapon/Dagger

The Type-10 Energy Weapon/Dagger, more commonly known as the Energy Dagger is a type of melee weapon utilized by the and the United Sangheili Republic for use by the Sangheili.
The energy Dagger is housed within the vambrace of a Sangheili's battle harness. Inside the vambrace is the Dagger energy storage, generation device and the blade projector. The Dagger is similar to other energy based weapons used by the Covenant, formed of superheated plasma and formed using a magnetic field generator. The battery used to power the Dagger is also contained within the vambrace, and has a very limited power supply.
The Dagger was designed during the Third Age of Conversion, when the Covenant Empire began its assimilation of the species. The typical Sangheili melee weapon, the Energy Sword proved too cumbersome to use in the close confines of Kig-yar ships and a new weapon needed to be designed. Taking the energy sword, shortening its blade and implementing it into the Sangheili's armored vambrace, the energy blade was the perfect weapon to counter Kig-yar and their specially designed melee weapons.
Ages later, the Dagger continues to see use but with a few improvements, particularly to the power supply. During the Human-Covenant War the Dagger was utilized in close urban combat with human forces and aboard their ships. When the Sangheili turned against the San 'Shyumm, the Dagger was responsible for the deaths of many Covenant leaders. The Dagger is still used by the United Sangheili Republic in its conflict against the remaining Covenant forces. 
Primarily a tool of assassination, execution, and brawling, in a few rare hands, it can be used to combat a sword wielder, parrying them dealing a death blow.