The second slave, initially with a high pride, so I used enforce rules to deal with her pride.
But the despair increased really fast, 1 despair instantly escape, 2 despair murder me, 3 despair instantly suicide.
I over rewarded her a pony to avoid her commiting suicide, but have to deal with her murdering, as a result, she became bony and weakened for a long time.
So her ranking was capped at F- because of F- beauty. It took me about half of the time to deal with that, during which time I just trained other skills only for increasing my skill level.
The reward was rich, enough to consider training an assistant.
This is my final attributes. I used the Katana-Swift Blow tactic again, but further usage of fighting skills require potions, so the next slave or next 2 slaves would be trained as witchdoctor.