I find both Acker and Strahovsky too soft as type. I think T'Prynn needs the coldness of a Jodie Foster.
Well, I can see where you might come away from Chuck
thinking that Strahovsky is too "soft." Her character's arc on that show is to go from cold and aloof to warm and affectionate. But if you look at the early episodes, she's more than capable of being quite cold.
But I can't imagine looking at Acker's performance as Illyria in Season Five of Angel
and not thinking she's perfectly capable of being cold and hard. She's absolutely chilling as Illyria.