Kig-Yar point defense gauntlet
From Halopedia, the Halo wiki
Summary
Jackals use personal energy shields for protection from enemy fire. Worn on the forearm, they create a barrier that can deflect any solid projectile weapon except rockets. It should be noted that grenades, even though deflected by the shield, can still explode and collapse the shield if detonated nearby.The shield reflects it's current charge by changing color gradually from its original color to red before it deactivates completely.
Energy-based weapons can penetrate the shield and can even collapse the shield altogether. The MJOLNIR armor's shield was devised by reverse-engineering the Jackal shields, it was later improved upon it to make it much more effiecient.
In Halo 2, the shield appears to have been weakened. It is now possible, if difficult, to bring down a shield with projectile weaponry, and a sniper round to the central dot will collapse it and stun the Jackal. However, the shield now provides the Jackals with limited melee protection.
There are two types of Jackal personal arm shields. Ones carried by minor Jackals are blue. And the other type, caried by major Jackals is yellow. Some Jackals (snipers) don't carry shields at all. In Halo 2, the blue shields are now green.
