The Line
Chain mail is the armor of the man who is paid to stand, and it is the tier where the armor stops being a coat and starts being a reason. Thousands of rings, each one a decision, each one a refusal — the mail is the argument that the cut goes around, not through, and the body behind it is the body that is still standing.
Chain mail is the siege tier: the line, the wall, the man at the front who is not flinching. It is the armor of the guild fighter, the professional, the one who has been stood against and is still here. A master chain mail has the maker's mark on the collar, and the collar is the part that takes the blow so the neck does not — which is the whole point, and the whole reason the chain mail is the armor that moves like a thought.
In the Hand
The chain mail is the armor tier where the AGI cost is real: −30, and the fighter who wears it is the fighter who has decided the argument is not about being fast. It is the answer to the flail, the answer to the long sword, and the question the plate asks: what if the body is the wall? The chain mail's answer is: the body is the wall, and the wall is the one who is still standing.
"The chain mail is not armor. The chain mail is a reason — and the reason is the one who is paid to stand." — guild master, The Company