Just to keep the thread near the top an idea about moods just came to me how about all moods are fell moods or at least a much higher amount dont think I ever had one in normal games 
Moods are hardcoded unfortunately.
As to the greater soulstone idea: don't you guys tend to find dark dwarf chunks are the first you use anyway? I mean, you have a constant supply of them and they are easy enough to acquire (Throw a wild animal in with a stationed dwarf). If you made them better you'd never use normal chunks.
I might still use the idea though, but maybe tie it to megabeasts instead

. Of course, we don't really need any more powerful weapons. If you want legendary superweapons, get moods with weaponsmiths and lock them in with adamantine =). If you are lucky you'll get a magic weapon from it and the damage from that will be utterly insane