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, similar to a Needler round. These blades may be relics from an earlier time for the Kig-Yar or simply outdated Covenant weaponry that has since been removed or replaced. It is also possible that the Master Chief never runs into an energy cutlass during the time of the halo trilogy.

Trivia

 * It is possible that the energy cutlass is actually a round from the Needler, or  made from the same material.
 * The Energy Cutlass was first mentioned in Halo: Contact Harvest.