I think that Halo 3 should be given more medals added to it because in my opinion it does not fit very well into the progression system. The fact of the matter is that Halo 3 simply has less common medals than the other Halo games. The solution 343 came up with was to greatly raise the XP rewards per-medal in Halo 3. So usually when playing H3 you’ll either get a ton of XP after a match or none at all. On top of that, completing certain challenges is significantly harder in H3. Challenges like “Style Browser” and “Objective Results” just to give an example.
I think the best solution would be to add some more common medals to the game. I think integrating the unified medal flasher would be a mistake, as it would take away from the style of the original game. So adding medals on a case-by-case basis would work best. Medal designs could be reused from Reach if applicable, since that game had a similar artstyle for medals. And of course you’d be able to disable the new medals if you’d like, similar to CE and H2C.
Below are medals that I think could be added without retracting from the original game:
(H3 Actually already tracks headshots and assists, there’s just no medal for it. No medal=no xp)
Ball Carrier Kill
(You get medals for killing the Flag Carrier or Bomb Carrier, doesn’t make sense not to have this)
(King of the Hill and Territories basically have zero objective medals. It’s near useless for completing the “Objective Results” challenge)