This feat opens you the possibility of learning to appraise items that you wouldn't able to do because your class, but you still have to find the proper teachers and do their quests.
When you train this feat you must specify a guild which isn't the one to which you belong, after it you are can learn to appraise items of both your guild and the one specified by this feat.
For example: Bob is a thief so he can learn to appraise treasure type items and trash type items, after finding the teacher and typing: Train 'Eye of Dragon' warrior, he can learn if he wishes how to appraise weapons and armour as well.