Easy Way to Get 'Vidmaster Challenge: Classic' Achievement

Getting this Achievement which is one step along the road to obtaining the Recon Armor, requires you to complete any level on Legendary difficulty without ever using a weapon or throwing a grenade. The best level to do this on is Uplift Reserve; simply get on the Warthog at the beginning of the level and quickly drive past the Wraiths and Choppers that are gunning for you. Switch to the Ghost when you first encounter it and boost through the next few areas; if you need a new Ghost along the way grab the one that's about halfway through the level. Keep boosting through until you reach the end of the level to unlock the Achievement.

Recon Armor

UNLOCKABLE	HOW TO UNLOCK
Vidmaster Challenge: Annual (Halo 3)	Complete Halo on 4-player Legendary LIVE co-op, with Iron, and everyone in Ghosts.
Vidmaster Challenge: Lightswitch (Halo 3)	Get the rank of Lieutenant in any playlist in the new EXP progression system.
Vidmaster Challenge: 7 on 7 (Halo 3)	Entered into a ranked or social playlist with 7 EXP on the 7th of the month.
Vidmaster Challenge: Brainpan (Halo 3)	Find all the hidden skulls on the Mythic maps.
Vidmaster Challenge: Classic (ODST)	Finish any level solo on Legendary, on LIVE, with no shots fired or grenades thrown.
Vidmaster Challenge: Endure (ODST)	In Firefight, on any mission, pass the 4th Set on 4-player Heroic LIVE co-op.
Vidmaster Challenge: Deja Vu (ODST)	Complete Highway on 4-player Legendary LIVE co-op with Iron, and no 'Hog or Scorpion.