Shield
Per fess abased dancette Gules and Or, overall issuing from the fess point of an ogress in base the rising cloud of an atomic bomb explosion Proper fimbriated of the second.
Crest
That for the regiments and separate battalions of the Nevada Army National Guard: From a wreath Or and Gules, within a garland of sagebrush a sledge and miner's drill crossed in saltire behind a pickax in pale Proper.
Motto
SOBRE TODO (Above The Rest).
Shield
The service of the former organization, the 221st Artillery is indicated by the jagged gold section which represents the Spring Mountains to the west of Las Vegas, the headquarters of the Battalion. The black circle indicates the Nevada Atomic Proving Grounds, which is a short distance from the Las Vegas Armory. The atomic bomb burst signifies that the Battalion was the first National Guard unit in history to witness and participate in one of the atomic exercises at the Proving Grounds.
Crest
The crest is that of the Nevada Army National Guard.
The coat of arms was originally approved for the 422d Antiaircraft Artillery Automatic Weapons Battalion on 8 December 1953. It was redesignated for the 221st Artillery Regiment on 20 May 1960. The insignia was redesignated for the 421st Regiment with the blazon and symbolism revised on 21 April 1997.