In Halo, Jackals wielded only Plasma Pistols, which ironically were the most effective weapon against them. Some Halo 2 screenshots show Jackals wielding Needlers. This one is shown with a Plasma Rifle. Of all the enemies that have so far been revealed for Halo 2, the Jackal model seems to have undergone the most revision since the first game.

The text reads:

Jackal. No Jar Jar. Are you still trying to decode this?