Oh ... I need to get my terminology right.
For the Field Barrier 3, you need to get to L50 on the Barrier Magic class. Field Barrier 2 is very good also, but you'll need to stay close to free MP rejuvenation area.
You're awfully close to a perfect spot for this. Let me know when you're done with that area.
(i'm doing my best to not spoil things)
OH ... hop onto the XBL market place and purchase the Blue Dragon "treasures" kit. It's 200 points and includes something you really want to have, the "Nothing Glasses". Every spot with a "Nothing" in it will have a green star on it.
Trust me, you don't want to miss a "nothing". There's 1,800 of them and they do have a purpose.