It was something I was thinking about back when I was doing the scripting for Cryosis' campaign. Right before the "assault rifle" gets attached to the MC in a cutscene (the MC cutscene is a different biped), you need to edit the script.
A long if-or-then type of statement needs to be created. the game needs to check what the player has, if the player has one weapon, then the game attaches that weapon to the movie MC. This "if" statement needs to be created for every possible weapon the MC can wield in the game. No worries since large "if" statements can be processed in a fraction of a second in Halo.
Why is this interesting? Well, Bungie did it for Halo 2, and I think Halo 3.
Most campaign maps, at least in my opinion, get converted back for PC. It's just another way to improve the campaign level and make the cinematic MC seem more like the one the player plays. Seriously, even on the Two Betrayals, the MC has an assault rifle, but begins with a plasma pistol and shotgun. Wow, makes you really feel like the same guy who challenged Guilty Spark with the words, "That's not going to happen."
Having MC hold the weapon you wield during a cutscene
I looked at it. he isn't using a particular weapons animation for the weapon. It's a cinematic one. Sniper rifle may look a bit awkward, as well as smaller weapons like pistols, but it should still work. I did a mod a long long time ago, the last spartans; he was holding a "sniper rifle" during the cutscene.
The script that gives the cinematic MC a weapon isn't to wield the weapon, just "attach" it to his hand.
The script that gives the cinematic MC a weapon isn't to wield the weapon, just "attach" it to his hand.