Here are few pointers
1. They will ask why changing line from engineering(which they perceive more better field to worK) to Banking. Blunt Ques. Why a Bank Job ( which literally means the same)
2.more salary in technical jobs and better increment and you will stick to your core field , so why bank job?
1. You can say I got interested in finance/accounts during final year seeing some in family blah.... you can fill in the blanks
2. Try justify your degree in this field is not a waste and explain what you gained etc and which help in your job you get the point
3. They will definetely ask you some thing on your grad knowledge
4. You will have Job Stability(not use security) Blabber abt how your friends are laid off w/o any reason you get the gist
Note: Interviewer perceive Engineering as a higher quality who should not be in banking. Also They want worker (read robots) who will work for them w/o asking questions which engg lot do not belong to.