I know a couple of version of him. This quest is also known as genkai5 the lvl cap remove quest that can make you advance till 75. Its a BCNM fight which you are going to fight your own self. Although Maat is (your current job)70/70Mnk. You have 10 min timer on this and you do not lose exp if you die in this BCNM.
Whm:
It is said you have to eighther endure for 5min not dying. Or heal for 4500 hps. It is still not clear. He uses spells such as silence, Banishga3, holy, dia2, blink, protect4 etc etc. Echo drops are a must. If you are silenced without echo drops you are pretty much screwed. The difficulty is said to be easy.
Thf:
You have to steal his instant warp scroll. Purely based on luck. You can have 2 goes. First try and make sure you have reraise on you. Then 2nd attempt after you revived.
Mnk:
He hits hard, he hits fast, he uses various mnk attacks himself. Way to beat him is said: Boost 10 times > Focus, Evade, 100Fists > Boost > Chiblast and engage > Raging fist > activate counter stance when Maat does 100fists > Icaros wing > Raging fists. This should down him.
Pld:
Key of victory is when to use invincible. Other than that, its just clashing swords. I don't know much in detail but you should beat him in less than 7min before Maat starts using his mnk WS.
Rdm:
Said to be the worst of all jobs. I beated him as rdm. Key of winning: Land full damage AeroIII 7~8 times to him. Using sleep is essential. Dispell his buffs is essential. Stopping his chain spell is essential. Boosting INT is a must. Fail all these and you have to go back to get another testimony. Oh and the Rdm testimony is found in one of the most annoying places and one of the most annoying mobs. Magic pots.
Since Maat himself is Mnk subbed, he will use Mnk ws such as dragon kick, one inch punch, and worst of all asuran fists. And worst of all he spam use the ws.