"Right. Well, take Carissa's artifact headband back to her, then, I apparently don't need it anymore and presumably that's the point."
Keltham quickly removes Carissa's headband and successfully ignores the resulting massive sense of loss and disorientation while he pops on the +4/+6/+6, because yes, it's obvious that if he tries to rebuild himself a personality it's better done at INT-25/WIS-26/CHA-25 than INT-27/WIS-26/CHA-23.