Well There's the Recon Armor but you have to work for Bungie or Win it or Do all the Vidmaster Challenges but you Need XBOX LIVE. Then theres the Bungie Armor and Flaming Recon and Flaming Hayabusa Head Pieces But you have to work at Bungie.
there isn't any
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
Armor does not effect your character's ability in any way. Just the appearance.
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.
no