|Mae is generally considered to be one of the worse blue mages in the game. This is in part due to her middling speed; most other blue mages heavily lean to some sort of fast offense. As such, at 31 base speed, Mae has nowhere near as much velocity as others like Ishtar or Kliff, nor does she have solidified niches in other areas such as M!Robin's high defense or Lute's ploy capabilities. However, she does sport the second-highest attack stat of all mages in the game at a base value of 36.
Because Mae's speed is lacking compared to other mages, she has the option of ditching it (at least in this build) for more raw power. As such, an attack boon is recommended. It's difficult to assess a proper bane, though Def is the likely the safest at a base value of 15. Of course, HP could work fine as well. Though, if you choose to merge her, this problem becomes null. The attack boon will grant her a staggering 39 base attack.
In order to accentuate her attack stat, Blarblade+ should be given to her. This will grant her 52 base attack on top of the damage bonuses from buffs. If she receives a full set of +6 buffs (such as from Tactic skills), she will garner a +30 attack (+24 from raw buffs, +6 from the actual buff to the attack stat), giving her 82 attack. Even from the weapon triangle disadvantage, she still gets ~65 attack. This will be important for later.
Her assist would be best off with Ardent Sacrifice or Reciprocal Aid. This build relies on Vantage, and through the assist is the safest way to do so. Her special, Blazing Wind, gives her slightly more player-phase use, as she then gets essentially two strikes that she would otherwise be unlikely to score. Of course, Glimmer could give her reliable damage in enemy phase as well.
Her A-skill is Close Counter. Nothing special, as she wants to be able to hit everyone at all times. Her B-skill is Vantage, so that she can hit foes first. As you can tell, her goal with this build is to strike first, ask questions later. With the Blarblade buffs, she has far more than enough might to kill most foes in one strike. Her seal, Fierce Stance 3, gives her even more might on enemy phase, though you may replace it with Atk+3 for better mixed-phase potential. You can also replace it with Heavy Blade to help her proc specials more often (this would be more useful with in-combat specials like Glimmer).
Her C-Skill is entirely flexible, though an Atk Wave skill would allow her to sustain some of her damage prowess on her own.