Pointing out the weaknesses.
I was playing a game against WarrenParish about a month ago. With a few nicely awkward tactics I had a decisive advantage - a Queen, Rook and a few advanced pawns against his King - and still had trouble achieving mate. At one point my opponent asked me why I didn't finish him quickly? I realised at that point that I didn't know my endgames (aye, for shame!). For me this game represents a turning point in my own Chess development for this very reason.
Below is the game.