If will is a personal property, it folllows that personal identity is located in freely willed actions. It means that a person is most fully herself when freely exercising the prerogative to initiate actions and make decisions. (Adonis Vidu, The Same God who works all things, p. 111)
What is a person? What is a person's identity? For one, it can be "tall, smart, black hair, male, Chinese," and for another, "eloquest, short, female, American." Personal identities, subjectively speaking, are intensively personal and pick up the traits that a person portrays as well as other distinguishing things about them. Objectively speaking, personal identities can cover all of the traits of a person, to identify that person against another.
Personal properties are of course the properties of a person, and thus key to their personal identities. So, in humans, if will is a personal property, is will part of their personal identity? For humans, of course not, because all humans have wills. The exercise of that will in action can form part of a person's identity (e.g. successful businessman), but that has nothing to do with the will per se but the will as acted out in the business actions he takes. Will we say that in humans, a person's identity is located in freely willed actions? No, because it is what is willed and what is done that identifies a person.
How then should we respond to Vidu's strange comment on will being a personal property? Vidu I think fails to differentiate being something being present, and something acted out. If will is a personal property, it can be said that a personal identity is that a person is a moral agent. However, the exercise of that will is an act, which the person can and does exercise. Therefore, it is a non sequitur to claim that "will" being a personal property implies that the personal identity is located in freely willed actions. The will is after all distinct from the act, though not separate from it.
There are of course more nuances when it comes to God, but the problem here is how Vidu, as with many of his Roman Catholic ressourcement friends, seem to think that a rejection of Aristotelian metaphysics and Aquinas is the cause of the problems with the world today (Modernism and Postmodernism). There are many problems with modernism and postmodernism, but making will a personal property has nothing to do with self-autonomy and the need for self-expression and self-actualization.