I didn't have that much trouble with the game on Legendary. Maybe because I played it all the way through on Heroic first and got used to the game before tackling Legendary.
Honestly, Solo legendary isnt that hard. Even more so, if you have 3 other people with you, you can literally AR storm the rooms and still kill everything on time haha.
My first halo game btw guys so...yeah ofc i struggled on legendary lol It wasn't too hard...over exaggerated there a bit. But the only parts that really gave me trouble were a few parts on the forerunner missions especially with the damn wraiths and then the last part on midnight where on the second tower you have to come and defeat a total of 6 knights. The commander with the incineration cannon kept killing me....i passed it eventually by kept shooting them with my light rifle at a distance lol
Gotta use those armor abilities man. Send out a hologram to trick him into shooting it and then run up while he is reloading the cannon and give him a scattershot to the face.