Fenrir is best used for defense, but mainly an anima defense team.
There was a glitch or typo in her Skill text, causing it to say that she Increased Phantom attack whenever she activated her skill, though this, however, did not affect the effect of the skill. The typo was later fixed.
Main: "I will devour Odin with a single bite."
Skill: "First of all I'll bite the arms to pieces, I think."