Freudian slip in an interview at the end. Definitely fumbled it.

Not prepared sufficiently my guy. Make sure you can think of a non-crucial skill that you're planning on developing and how you're going to do it. 

“Obsessed with prestige” but can’t get a job in IB, can’t get decent A Levels and didn’t go to a target university. Lol

I actually Lol'd. I don't like that answer to your weakness tho. Not achieving goals (regardless of how high) wouldn't be something I'd flaunt despite your efforts to spin it in a positive light. My advice would be to play it safe with the classic 'perfectionist' weakness saying how you can sometimes spend too long on a task because you want to make sure it's perfect -- the 'how long could you polish a quarter scenario'. This answer always gives IB interviewers a hard-on cuz that's literally an analyst's job. 

Setting unrealistic goals and consistently failing to hit them isn't a weakness to advertise. It just makes you look incompetent with a naïve ego to boot. The answer was a symptom of a much larger problem of a severe recurring inability to gauge your own capabilities which any interviewer worth a damn that gets your first answer will likely catch on to and ding you for from the get go. Your slip up was just adding insult to an already gaping injury. You're better off with something like "I sometimes get sucked into the weeds of projects and end up overanalyzing things to the point where I get buried in details rather than focusing on the big picture" because at least that alludes to you being thoroughly detail-oriented (an inherent positive for an analyst candidate) while being something they can easily envision training you out of. 

Where does the arrogance come from though?

You went to a mediocre college and have not secured even one top job offer.

Don’t you need to have even a modicum of success to be this arrogant?

This guy again.