Leather Armor is a type of Armor that can be made with the tailoring skill from levels 5-7. Leather Arms give 6 AR, Leather Legs give 13, and Leather Breasts give 16. A full set of Leather Armor thus provides a total of 35 AR. One can achieve a slightly higher AR value by wearing Leather Arms over a Robe of Protection, for a combined AR of 36.
Wizards can not cast their magic when wearing leather, so they are forced to stick with Robes of Protection, making them the class with the least Armor Rating. Rogues also find it good for Stealth, as leather armor only slightly penalizes the stealth skill. Rangers and Fighters have almost no need for leather armor, however, they can be useful when facing Rust Beasts.
For most of its existence, a full set of Leather Armor provided considerably less AR than the combination of a RoP and Leather Arms. In the March 2012 update, Leather Armor was given a boost, but a full set was still not preferable. Then, in the next month, a patch was released that raised the AR of Leather Breasts to 20 – the same as Plate Breasts. Suddenly, Clerics and Druids became fond of wearing full Leather Armor, as it bestowed a total of 39 AR. Thereupon, the choice between Leather and RoPs was a tradeoff between utility and fashion. Leather Armor was also popular because it is easily obtained, relative to a Robe of Protection.
Just over a year later, in the May 2013 update, Leather Breast AR was reduced to 16. Since then, the armor values have not changed.