Here’s a list of SOME, but not all, the words that you may see in a long passage where the author starts the concession point.
The concession is where the author says something good to praise the previous works and then there’s a shift (words such as but, however,…) to make her/his point. That’s what @gregmat calls the “Hammer”. So, the Hammer is the author’s opinion.
A real life example:
Indeed, Greg is a great mentor. However, 
