I dont know if anyone posted anything like this before since the search is broken.
Since this will be set about 2 decades before the first Halo game, which human weapons do you expect NOT to see. Necessity is the mother of invention, and when the whole human race starting to be pressed for survival, there would be a lot of money being poured into weapon/war technology reasearch and development.
Im guessing the spartan laser wont be in Halo Wars due to how rare it is in Halo 3 campaign. It was mostly likely very expensive and still experimental so its not widely used. If you dissagree with, go ahead, back it up, but no flaming please.

It's safe to come out. This is Sergeant Spits.. en... son... gen. -A Grunt