@fangorn
1.) Hera cybella as a GR or GS are both good but 1 way of using the Hera cybella that might be better in arena is using her as a GR. Why GR? The knockback if she cries on the backline archers can seriously hamper the opponent's trigger combo if you are faced with those situation. You can also knockback one of those annoying tile holders and she's amazingly decent for pve content as well if you have another Hera Kane GR or Hera Cybella GS to proc her combo. Take GR if you lack some CC.
2.) PVE:
Lucille Inquistor
Kai Ninja (For Gold mine and for combat purposes. Ares is good for the high dps burst)
Victoria HD (Convert from your Crusader)
Teresa WD (Skill delay is strong)
Cybella GR/GS (Both viable but based on the above reason, I would choose GR)
PVP:
Kai Ninja
Victoria CK
Teresa WD
Cybella GR
1 more DPS. But if no DPS maybe Lucille can fit in the bill for now.
Generally you will want to bait opponent to move in so that you can go in for the kill and stuff.. your strength of your dmg will derive from the kai ninja and cybella gr for control. both the ninja and ck are good for combat tricks as well (tile swapping)
Hope that helps.