Hello community,

I'm a new player, and wanted to kindly ask all ye veterans to explain to me some things i've come across in the game.

1) What does the Luck stat do ? And is it any worth spending achievement slots on it ?
2) Regarding achievements: Is it better to increase the primary stats of my gladiator or are the +Attack/Defense achievements more beneficial to have ? If it's a question of gear/lvl then when is the approximate transition to occur (lvl or gear wise) ?
3) I would also be most obliged if anyone could suggest any achievement bonuses that a defensive 2H War or a Dual-wield exotics Theatrics glad should focus on (stat-wise, not particular achievements).

A warm thank you to anyone who cares to share their knowledge.