Gear progression as I see it...
AF armor / lv44 GC Weapon >>> do Amdapor once
-- Start your relic quest
AF armor / lv50 GC Weapon >>> farm Ifrit for weapon
AF armor / Ifrit's >>> farm Amdpaor for armor
Amdapor / Ifrit's >>> Garuda (at least once, maybe farm)
Invest in Darklight accessories (they're cheeper and usually a better upgrade than over AK armor)
If you have Ifrit/garuda weapon + AK armor + Darklight accessories you can beat Titan Hm... it gets easier with more gear, so continue to invest in Darklight while you learn the fight.

Once you beat Titan HM, you should have at least half-Darklight and your relic weapon. You may have purchased a piece or two of AF2 armor with Mythology and are ready to start looking at Coil. Again higher level gear makes this easier.