What's wrong with fatalis? He was a pretty reasonable boss fight using melee weapons.
In the older MH games on PS2 and PSP, Fatalis was a pain to melee. If its leg or tail hit you then you're either killed in one hit or two.
That and there was nothing higher then green sharpness, so unless you got lucky and could his his face, you are going to bounce.
You could use minds eye, but then your attacks would still do less damage.