There seems to be an issue with the profession XP rewards at ranks 14-16 of the Mailsmithing profession with the Scale-type (ie. Great Weapon Fighter use) shirt & pant items, ie. the "Ornate" and "Fancy" grades. Both the shirt/pants and gambeson/trousers variants only give 500 profession XP, when the equivalent Chain (ie. Devoted Cleric use) ones at the exact same profession ranks give 1,125 instead.
Apparently someone plain done forgot to re-scale the rewards to current standards.
Also filed a ticket in-game about this, but I figure it doesn't hurt to post here too.