Hi QA folks!
I thought I read a bug report about this - but I couldn't find it anymore. Sorry.
This is an old bug but it seems it never got fixed.
So: If you play a Soulblade/Fighter and kill an enemy with Soul Annihilation you will not get an additional attack from Cleaving Stance. Imagine that: not a single one. That's somewhat disappointing.
It seems that Soul Annihilation isn't considered a melee attack when it comes to Cleaving Stance - which it totally is. But I can't say for sure.
Anyway: doesn't work. No savegame needed (I guess) since you can reproduce this easily with any Soulblade/Fighter.