Yes, that Magnum. Halo: Anniversary's multiplayer is based on the Halo: Reach engine so you know what to expect in that regard. However, 343 has revealed that the Magnum pistol from the original Halo will be usable in the multiplayer. Specifically, the Magnum will be wieldable in special and classic playlists.
As for the rest of the multiplayer, 343 is planning a big update set to hit this October. The update will address a number of things, such as armor abilities. Armor Lock will now absorb a level of damage based on the remaining energy a player has. Active Camo's duration will also be reduced.
Another fix makes it so that players can no longer block sword attacks with their guns. Only swords will be able to block sword attacks, which realistically makes sense. Reticle bloom will finally be configurable as well for increased accuracy.
Are these updates welcome changes to all of you playing Halo: Reach?