Zen, many people have praised this as a well written fic, dispite their disagreement with your treatment of Akane. I would add mine to those. I would also like to call your attention to this segment:

She hadn't known what she was fighting, or how to fight it.  She had

been all of six years old.  She had expected the shadow that came to
steal her mother would be like another person - and that if she were
there - if she were ready - she could defeat the shadow and save her
mother.

But the shadow had come in the dead of night.  While Akane slept,
her tear-stained face buried in a pillow at her mother's bedside, the
shadow had stolen her mother's life.

It had taken the family months to convince Akane that it had not
been her fault - that there was nothing that she could have done, no
way she could have fought the demon that had torn her family apart.
There were times when Kasumi was not so sure that they ever *had*
convinced Akane...

Akane had recovered eventually.  At least on the surface, she was a
normal schoolgirl - but she had become obsessed with the Art - with
learning to fight better - beneath that surface there seethed a mass
of raw emotion of tremendous power.  Even Kasumi had not truly
suspected its intensity until Ranma had come into their lives, and
had broken through Akane's armour - and while it had let him in to
her heart, it had also let the turmoil out.<<

This is your explanation of Akane's rage disorder. A short while before this segment, we learn that Akane could be suffering from this disorder. Now we are handed the possible source of the problem. It's too sudden. We have no prior clues as to this, and no further mention of it after. 
You could try to insert some clues such as during Akane's fits of rage as to why she has to defeat Ranma because of this, why she cannot afford to lose. Even little sentences will do.
If you did put them in, sorry I didn't notice them.
And you made very little mention of Akane. It seems to me that you avoided writting about her unless you had to.