You have an interesting question regarding the appropriateness of a dressy shirt with a black pant suit. Actually it sounds like a great look providing the blouse isn't too gauzy or too low cut. As long as the pant suit is appropriate to the occasion the blouse should be a nice fashion accent.
For almost any venue a black suit with a light, feminine blouse is good choice; it softens the lines of the suit without being too "sweet". If you still have doubts, why not wear something more conservative with the pant suit and save the lovely blouse for a more casual (and happy) event?