He 'tempered' his criticism 'with' a few words of encouragement. = He 'tempered' his criticism 'by' adding a few words of encouragement.
He was upset but 'kept his temper'. [=remained calm; did not become angry, begin shouting, etc.]
Higher interest rates have 'tempered' [='lessened'] the demand for new houses.
(..) boyfriends before Albert, and those ended badly, too, huh? Too? My mom and Albert were happy. His temper, the fighting, his wanting you to move out. He didn't want that. We were close, all of us. That's not what your mother said. (..)2014 TvShow: Bones Title: The Master in the Slop Season: 9 Episode 14
(..) I would never do any... You didn't love Albert. Nobody did. Even your mom said that he was volatile and had a temper. People would say that you did the world a favor by taking him out. What Sweets is saying is absurd. It's called developing themes. (..)2014 TvShow: Bones Title: The Master in the Slop Season: 9 Episode 14