The armor's appearance is exactly identical to regular leather armor.
You will only get to use this armor while you are fighting in the Legion arena. After the fight, the armor will be taken from you. This makes the armor quite unique.
It is possible to obtain this armor through glitches, as soon as the fight starts run out the gate before it closes and you can receive your belongings in the arena storage footlocker.
Getting the armor out of the Fort seems to remove its Agility bonus. It will also be considered a quest item and will not be removable from your inventory, but since it is a quest item, the 15 WG will not count against your carry capacity, as all quest items are functionally weightless.
If you have taken the armor from the arena, you can remove it from your inventory by shooting the opponents from outside Caesar's tent; if you wish to keep it, ensure your followers or Legion guards do not kill the opponents.