Soft luster is a type of finish that is often used to describe the appearance of metal surfaces. It is characterized by a smooth, glossy look that is not overly shiny. The two crossword solutions for this term are 'SHEEN' and 'PATINA'. SHEEN is a five-letter word that refers to a soft, subtle shine on a surface, while PATINA is a six-letter word that describes a thin layer of discoloration or oxidation on a metal surface that gives it a unique look. Both SHEEN and PATINA can be used to describe the soft luster of a metal surface.