I don't think an MSc Physics is going to help you particularly but if you're interested in it then you should do it; it's only going to be one year out of a forty five year career! Also, you will impress recruiters with such a degree (although your Bachelors will already have impressed most of them, which is the only reason why it won't make much difference).
I wouldn't worry too much about relevance either. Physics will give you the raw skills and demonstrate your talent to succeed and your future employer will give you all the training you need. Heck, they trained me and I have an irrelevant History degree!