atm Diana.
And Artemis has high spike damage on top of her def debuff. You can't really expect more. Overall light's damages won't be outstanding until Nike / AW Michael. If it bothers you, go for fire , wind or thunder.
Until then, you can still replace Eros with Michael (or Frey when she becomes available), but that's not how light shines...
-Triya is also very good. Right now i don't think i'll even aim for Artemis at all. Since Nike is released at the same time i'll probably save my jewels for her. Until then, Diana will be enough. I'm also very curious about the last one, Takeinakata.
-Yes
-Eros it's : -20% atk, a spell to prevent debuff (like Amon or Poseidon) + a forgettable ability dmg buff (still better than nothing), a barrier that absorb 1200 dmg every 6 turns during 3 turns, paired with a defense buff (15/20% i think?). With her + AW Sol, your team becomes kinda unkillable.
Here is a (random) vid if you wan't to see how she works :
https://www.youtube.com/watch?v=xHgzGvvc2w4