Energy cutlass

An Energy Cutlass is a Kig-Yar melee weapon. It is the shape of a shard of glass and is pink in color. The Jackals use them primarily to dispatch enemies in close-quarters fights, especially when boarding an enemy ship. They are similar to the UNSC Combat Knife. These blades house a complex chemical mixture within them that causes the knife to explode into shards when embedded into a soft target. These blades may be relics from an earlier time for the Kig-Yar or simply outdated Covenant weaponry that has since been removed or replaced.

Trivia
It is possible that the energy cutlass is actually a needle round from the needler.