"Skill is the sum of all applications that a designer has ever designed."
Most designers are born with good taste and the aptitude to convert this into design. There are people who can draw well and people who cannot draw at all. How well you can draw depends on how often you draw. It is the sum of all designs that a designer has ever designed.
The more interfaces a designer has created, the better he knows which fonts work, which colours go well together, or whether a screen has the right rhythm or not. The more often a designer is given feedback from a developer, the better his designs will anticipate their needs.
"Empathy means being able to leave behind your own assumptions"
Empathy depends less on aptitude than skill. It's a question of being able to set aside your own assumptions to assess the impact that the situation has on the interface. It is often simply a question of common sense.
Take an online change of address form where the user has to fill in technical information such as the numbers of electricity or water connections. When designing the change of address form, it is best to take account of the fact that the form will not be filled in all at once. The chance that the user will be at his old and his new address at the same time is very small. This is the context that determines how easy it is to fill in the form. There are two possibilities. Either you allow the form to be filled in at different times. Or you help people to gather all the information required before they start filling in the form.
When we hire designers, we look for both skill and empathy. We prefer a designer with a less flashy yet well-considered portfolio rather than a couple of isolated screens. We want to see his or her evolution as a designer and assess his or her potential.