You have to find all the skulls in campaign mode.
You have to complete achievements and levels. For example, beating the campaign on normal gets you EVA along the way. Grabbing skulls also gets you Hayubusa (aka ninja) armor (which I have).
http://hubpages.com/hub/Halo-3-Armor
No, there is no armor in Halo 3 that has a knife in the shoulder.
There is no Brute armor in Halo 3, only Elite and Spartan models.
go to http://hubpages.com/hub/Halo-3-Armor
you get all the vidmaster achievements on halo 3 and halo 3 odst
NO
recon armor
the same way in halo 3 because when you play halo 3 mythic it says your playing halo 3
there is no permanent cheats in halo 3. you need to unlock them by achievments. and, you can not get the flaming armor effect, it is only for bungie employees. in halo reach, buy the legendary package to get that armor effect.
Hayabusa
You cant!