Heroic Traits
For Heroic Traits, it really is just personal preference.
I feel that the ones I recommend would be the best choices for Luminary and the other ones are viable for other uses.
Recommended
Apostle
Stat Bonus:
INT +10%, MATK +5%
This trait is great for increasing your Damage Output. So if you want to do more damage I would highly suggest using this trait. Very good for end game purposes.
Crack Shot
Stat Bonus:
LCK +10%, Mcrit DMG +10%
This trait is good if you want more LCK which will contribute to Accuracy and Mcrit Rate. Also provides Mcrit DMG which determines the Damage done upon Criticals, the multiplier. The cap at which Mcrit DMG can go up to is 3.00 so 3x the Damage on a Critical. The total amount of Mcrit DMG given from this trait is equal to (0.10). Good trait if you need more accuracy and want to land more critical damage.
Others
Leadership
Stat Bonus:
HP and MP +12%
A decent trait that works well for all classes. If you like to play more than just Luminary this would be a good trait. HP is a really important factor near end game, lots of players as well as monsters can do hefty damage if not properly geared. MP is great for Lumi because Lumi relies so much on skill combos which drains a bit of MP.
Guardian
Stat Bonus:
Defense +10%, Elemental Resistance +5%
A survival trait which helps lower damage done by Physical and Magical users. Good trait if you feel like you might be too squishy as a Luminary. Would be beneficial if you decide to use a Shield on Lumi, but heavily cuts down on Lumi's Damage output.
Maverick
Stat Bonus:
AGI +10%, Attack Speed +5%
A good trait if you plan to build Evasion. All around good trait for all classes. Atk Spd does help with Luminary's basic attacks, but not as potent as the magical dmg of it's skills.