What is Beneficial Power?

Legal Definition
In New York law and practice. A power which has for its object the donee of the power, and which is to be executed solely for his banefit; as distinguished from a trust power, which has for its object a person other than the donee, and is to be executed solely for the benefit of such person. Jennings v. Conboy, 73 N. Y. 234; Rev. St. N. Y. ยง 79.
-- Black's Law Dictionary
Legal Definition
The power of a donee to use property for his own benefit.
-- Ballentine's Law Dictionary