Tanking Titan is super easy...in fact the Tank has the easiest job out of all classes for that fight. I would highly recommend you get over 5200 HP before trying though. This means full DL accessories (you need an earring...seriously...), full AK gear for other slots with Ifrit weapon minimum. This is very doable with that gear provided the rest of your team is up to snuff with dodging & healing. More is always better though as you need to be able to survive some of the high damage moves he does.