The Dragon Mail is a high ranked heavy armor in Final Fantasy XII that boosts the wearer's Defense by 57 (Zodiac) or 53 (original), HP by 100 and Strength by 8. Uniquely for a heavy armor, the Dragon Mail gives HP, usually a property reserved for light armor. Strength is the biggest boon of heavy armor and so it is usually a good strategy to equip whatever gives the best Strength.
In the original PlayStation 2 version, the Dragon Mail is sold for 12,500 gil in Balfonheim Port after obtaining the Treaty-Blade, and is among the best purchasable armor and thus potential endgame equipment. It is found as a treasure in Barheim Passage's West Annex (near the area where the path starts to narrow; 70% chance to appear, 90% chance for gil, 50% chance the item treasure is the Dragon Mail without the Diamond Armlet ), and Cerobi Steppe's The Northsward (50% chance to appear, 50% chance for gil, 10% chance the item treasure is the Dragon Mail with the Diamond Armlet equipped ). It os rarely stolen from the Dark Lord, and is available through the Hunt Club on the Phon Coast by giving Blok 20 Rare Game trophies and then buying it from the Shifty-Eyed Merchant's store for 11,250 gil.
In the updated Zodiac versions, the Dragon Mail is not sold in normal shops but sells for for 5,750 gil. It is found as a treasure in Cerobi Steppe's Old Elanise Road (20% chance to appear, 50% chance for gil, 5% chance the item treasure is the Dragon Mail with the Diamond Armlet equipped) and Pharos - Second Ascent's Station of Ascension (always appears). It is still rarely stolen from the Dark Lord, and now also from Pallicant in Trial Mode Stage 43.
Dragon Mail is a high level armor giving 57 or 53 Defense depending on version, 100 HP and 8 Strength. Its stats make it a contender for endgame equipment; though its HP boost is not so great, any HP increase can be worthwhile and its other stats are good, though fall short of the top tier armor (Genji Armor, Maximillian and Grand Armor). The strength bonuses make heavy armor ideal for frontline fighters, and the Dragon Mail is a good helm to equip over any inferior equipment the player may have on anyone who attacks physically, although a gun-wielder does not benefit from the strength-boost.
In the Zodiac versions, Uhlan, Knight, Time Battlemage, and Foebreaker can equip it natively, and the Red Battlemage can learn it if they unlock Exodus, the Archer can learn it if they unlock Shemhazai, and the Bushi can learn if they unlock Zodiark on their License Board. Dragon Mail is only useful to look for if the player has chosen these License Boards for the party. The player is most likely to obtain the Dragon Mail from Pharos in these versions, and so they will have Shemhazai from the story already, and Archer's unlock with it is among the better ones.
In The Zodiac Age versions, after fighting Belias the player can choose two License Boards per party member and so more characters can benefit from heavy armor, as it is usually a good idea to match jobs that use different types of armor to bolster light armor jobs' strength, and to give more durability to spellcasters.