This topic has been addressed to some degree and those topics are now closed. Most suggestions are basically feed a potion to your thrall and roll again for new perks. But what if…
Drinking a Yellow Lotus not only reset the thrall perks but the thrall XP?
Now that thralls can ingest potions I tried a Yellow Lotus to no affect on another thrall I’m ready to let go. I have already broken bonds on two thralls. They were trained to level 15 and I refused to complete their training. So I have had to farm wild-surges for new T3 fighters, make them friends and then train them.
I was hoping the Yellow Lotus potion would reset the perks but was expecting the experience points would also reset. So I would have to retrain from zero and I was fine with that. This method spares me from farming for another T3. It might not seem like much but if you finally found that cute thrall only to have her turn into a survivalist (or worse) with no strength or HP, well that is such a waste.