This is partly why I'm not sure about the ST stat at all. It could all just be rolled into HP, since HP could also be used to denote mental health as well as physical. People get too wrapped up in the idea that losing HP should mean getting hit, but it doesn't have to be. It just represents how much you're losing.
The PS3 game Uncharted uses a mechanic that explains why the main character can get 'shot' over and over and not die: every time you lose 'health', you're losing luck. The only shot that actually lands is the one that kills you, becasue your luck has run out.
If we only had HP, then they'd be drawing down on HP the entire time, which would have ended this fight faster.