GC ranking and fate exp cap?

I have a question. My brother recently rejoin the game after quitting 1.0 and he is now grinding fate for exp. He told me today he get less fate exp than his friend. He is lvl 37 and he is fating near windport. He get like 8k experience for fate while his friend get like 11k for the same fate. His GC rating is lower but his promotion quest don;t come till like 42. What could be the reason for his exp cap?

Fate EXP is determined by level. The more levels you are under the Fate's level, the less EXP you get.

theres 2 reassons:
- if his lower lvl then the fate, then he wont get full exp
- the other person is not using there main class, which means they get 50% exp bonus from fates.