See, the thing with Ghost Flame is that their defense bonuses really starts sucking at high levels, since it doesn't scale much more than at level 10, so it's not worth getting the skill at all, especially since it doesn't make much difference in a game where the name of the game is not to get hit even if they wear one armor tier higher than elemental bombers. Remember, both are glass nukes, which is why they need to be far more mobile than they seem at first.
And yes, I see what you mean about Perfectionist but there's enough sp that you can carefully spend into to get the title because it only unlocks when you spend all points at level 70, NOT when you ding level 70 with zero points.
EDIT: I notice I'm seeming a little harsh, but I don't think Ghost Flame is worth it at all as a buff imho. ANd yeah, I derp'd hard somehow and misread ghost flame as flame shield. Sorry about that.
EDIT2: I'm now really liking avengers at the moment, their damage potential is actually good even without the cubes, just gotta have good sense of comboing well with Devil Strike and planning around your easily stopped skills.