Advice on Skill Enchanting

Hi all. I am leveling a Aeore Eva's Saint (pve focused). I have some questions around skill enchanting on the following skills.
.
Dark Backfire:
Hex vs Mind: Decrease P.Def or M.Def. I see most groups melee oriented so I think P.Def decrease would be more helpful
Change: Some as above

Mass Mana Gain:
Shield vs Magic Shield: What would make more sense for high-level PvE (I think more threatening are raid bosses magic skills) so M.Def would make more sense, right?

Thanks in advance

Advice on Skill Enchanting