A stat that is compared with an attacker's dexterity to determine the likelihood that the enemy's blow will be a critical. Agility also has a direct impact on a character's evasion, shield, parry, and ranged accuracy stats. For every two points of AGI a character has, these stats are raised by one point.
In addition, Agility plays a significant role in determining the damage caused by Trick Attack when used by a Thief.
AGI is the key difference between haubergeon and hauberk
I don't agree when you say bst don't need that 10 evasion this piece is a lot better for bst and tried the Haubergeon and i say that the Hauberk wins when it comes to bst
It's hard to say the Hauberk is "arguably worse" than the Haubergeon, because, it simply isn't. For Lv75 usage by the jobs able to wear Hauberk, Hauberk is better. If perhaps one includes a good amount of 60 cap matches or has other jobs that can only use Haubergeon, then perhaps it would be a good time for that.
PS: as Jackryan quoted from FFXIclopedia, AGI also can play some roll in crit-hits, making it also better for end-game for those jobs able to use it.
Just want to clear something up:
For the person that is only leveling one job that can equip a haubergeon or a hauberk, then the thing to do is buy a haubergeon at level 59, and then level to 69, and then, at least on my server, you can sell your haubergeon, and then buy a hauberk, and actually MAKE A PROFIT! Then again that's only if you want to level one job. Otherwise you obviously keep your haubergeon.