Your experience as a lawyer is very irrelevant imo. It is very easy for an investment banker to become a M&A lawyer after a few years of work, but not vice versa. The same applies for most of corporate practice. You should have come to realize this if you've been in it for a few years. Corporate law is not difficult at all for intelligent people, most bulge bracket bankers I know pretty much know the Listing Rules at least as well as me, if not better.

Are you good quantitatively? Are you familiar with advanced modelling (even in Excel, not to mention other technologies like Stata or Python which some banks use)? Are you prepared to be tested on this in an interview? Do you know how to perform regression analysis, up to at least a Gaussian process model?

Your post does have some ambiguity. If you are looking to take on a non-quant role, then go ahead. But I don't see why you would - it's less prestige and less money.