Dominant Fi: Arwen always stays true to her internal self. Against everyone else's wishes, she chooses to become mortal, because she knows it is the only way she will ever be truly happy.
Auxiliary Ne: Arwen sees clearly what could be and is very future-oriented. Arwen is also abstract. She can see the connection between seemingly separate things. She trains Aragorn's horse, she makes an enchanted standard powerful enough to convince the dead, she makes sure Aragorn gets said standard when he comes near the Paths of the Dead, she makes sure Aragorn gets the Elessar. These are all seemingly separate events, but they are all crucial to making Aragorn king, which is something Arwen is well aware of (see my essay for details).
Tertiary Si: Arwen clings to Lothlórien throughout her life and never gives up her elven culture.
Inferior Te: Arwen has no problem organizing and putting her plans into action.