Visionary architect Gae Aulenti finds these 4 traits most critical to a great architect. IMO, this is just as applicable to the design profession.
1. Analytic talent
Know how to study and recognize every different kind of architecture, to create unique, specific solutions with respect to their context, their foundation place.
2. Synthetic talent
Know how to make the necessary synthesis to give priority to the major architectural principles, to disregard what is arbitrary in a project.
3. Prophetic capacity
Embrace the art, poetry, and aspiration for invention for your project.
Surface and understand Biases.