Three weapons glitch

This glitch will allow you to have three different weapons to hold at once in Halo. Tested on Legendary

This requires that you are on Pillar of Autumn. I'd recommend not using Easy due to its different level design (I haven't got it to work on Easy yet)

At the start go to the Captain as soon as you can. Skip the cutscene, get out of the safe area. Hopefully no grunts will appear, nor will you get a pistol (Otherwise, restart level).

Quickly get an Assault Rifle and a Plasma Rifle. Go back to Keyes then go out, the grunts should appear and you should have a Pistol, Assault Rifle and a Plasma Rifle. You can change the weapons without any problems. Scroll through them like you'd normally do.

This made it possible for me to beat the first level on Legendary, so it's a glitch and a cheat.