With all of the extra levels he has recently gained, Cain found himself with a wealth of points to put into his [Lord of Horrors] secondary skill tree that he received along with the [Horrific Perfection] reward.
The most obvious lack of abilities for his puppets was going to be in the field of child care, so Cain put an entire ten points towards the category, making every Puppet as skilled as any professional Governess and Nanny.
That increase Unlocked the next rank of skills in the Lord of Horrors tree, with only 3 options. All of them grant an additional skill for Puppets, and it reveals that only one single skill is in the rank above them.
As it stands, he has enough points to select all the additional skill slots if he wants, or he could add journeyman level talent in more trades to every Puppet instead.