This is a pretty straight forward strategy on how to defeat Maat without anything fancy. It has worked for multiple people and is worth posting. You can, butdon't need to sleep yourself to 100%tp. You should take at least a couple hi-potions just in case (especially if going to fight Maat at lvl 66 or 67). It is also helpful to have a Carapace body piece. Blink Band, Stoneskin items also help, but are not needed.
Basically upon entering the fight, you run until Maat is in view. Soul Voice, double Paeon, Requiem Maat, then Elegy him. If you've got decent defense and a decent attack, go ahead and melee him WSing whenever you can. If you're short on funds, simply kite him, resinging Requiem before Soul Voice wears off. Soul Voice + Requiem, if put on him soon after entering the fight, will pretty much kill him without any help. Just be sure to dispel any Paeons he might put on himself as well as pop a hi-pot to stay in the white HP range. When I did this strategy and used a sword, I beat him in about 5 minutes with full hp, using only one hi-potion to max my Spirits Within.