She had always been addressed or seen as a whore, so even though she was now dead, he wanted to honor her by giving her the prestigious position of a noble.
Ainz couldn't help but think about his bargain with Spartan after he had left, and a small smile appeared on his face, when he said he wanted ten percent, of course, he knew he was shooting too high, and would be rejected even the five percent he managed to bargain would also have been rejected if not for several factors.
However, the reason he managed to get that much was on the prerequisite that he was a rare dual element mage and a cultivator.
Secondly, was that he stated that he didn't require any cultivation method or techniques from the ancestral ground, this was what made Spartan agree to his request.