My two mains are BLM and AST. However I play more AST because of the intricacies of the class. Like everyone on here suggest MND, MND, and more MND lol. The only time I have ever had any mana issues is when I am having to revive other people or my party in raid or dungeon fell short so bad I had to light speed heals like crazy (mainly due to the the DPS having to be tank because tank can hold agro). MND is better for AST, also remember the ewr+balance/bole (royal roads)=mp regen extreme in case you want to hold on to luminous aether in a tight bind ( I use my ewr on myself, WHM, or DRK).

your armor and accessories will pick up the slack on peity and if your luck is good even spell speed that has help me out of some good binds being at least a sec quicker on my heals