INFJs don't tend to manifest that "fencing" attitude (IMO). They're more likely to try to use the opportunity to facilitate some kind of personal connection. I think of INTJs as the "fencers" when asked about personal or private matters.
Now I don't think I'm a cookie-cutter INFJ by any means, but did want to address this comment. I actually do quite a bit of 'fencing' with strangers, or anyone who is not a close friend. I don't enjoy talking about myself, and much prefer to hear about the other person.
I do agree about the personal connection piece..but for me, I try to get the other person to open up more, and then connect based off of what the other person says, and find common ground in that way. Yes, I'm able to talk about more personal matters, but I definitely 'deflect' initially.
Once I'm really comfortable with a person, I may open up quite a lot - but in an interview setting, I would totally be more guarded, and would only show certain aspects of myself, and would keep other pieces carefully hidden. A male INFJ coworker is much like this -- I never saw any of his emotional side until I got to know him quite well. I was actually surprised when he told me he tested INFJ - I had assumed he was a T because I never saw the emotional side. But since then, I've gotten to know him better, and we've realized we're a lot alike, and we are quite free in more of our emotional responses, and don't hold much back. Two other INFJ female friends that I have are equally guarded with strangers, and it's only with time that you discover the rich inner emotional world, and more openness in their personal experiences.
I haven't watched or read any of Cate Blanchett's interviews by the way..I just wanted to comment on this piece, and I don't think this 'fencing' thing is necessarily in opposition to INFJ.