[You should focus on one ability to study and after that, you can study your other abilities.]
Bello advised Ainsley to have one or two ace offensive abilities, just like the Godfather's blood-manipulation ability and the God Of Thunder ability.
The Godfather's non-offensive ace ability was his domination ability.
In Bello's opinion, Ainsley should focus on luck manipulation and shaman ability as her ace offensive abilities while her baby charm became her ace non-offensive ability.
After all, even though charm could be used to kill, it had many features more suitable than killing people.
But since using too much luck-manipulation ability has its own price, it should be Ain's trump card instead.
For general uses, it was better to hone her shaman ability and quickly use the blood manipulation ability without needing the Godfather to possess her every single time.