How dose the game calculate Fortify Health?

Let me explain.

Say my character is wearing fortify health ring or armour she manage to kill her enemy but her enemy left her one health point. I took that ring or armour off expecting my character will die but she did not. Why?

If the amount of hitpoints after removing the Fortify health effect would be less than one the HP will stay at 1. That propably is intended to avoid accidental deaths.

Well there is always a reload. I wish it works like Fortify Strength. When you loose a Fortify Strength you loose that and go back your levelled strength. I know what you typed about and they way the game dose it, its good attention but I prefer fortify spells and enhancements work the same, when you loose it or time limit is up, you go back to your actual and/or negative you loose fatigue and drop down or die you loose your fortify health.