Verb (used with object), verb (used without object) : Avarice had harshened his features.    From Dictionary.com. 

I refuse to let the hate get on me lest it change my natural charm and harshen my fluffy self.    From Wordnik.com.  [Gore!] Reference

(He rewrote Ghosts -- at age 85, mind you -- with loads of obscenities to harshen the inter-familial accusations even more, and drew out the final death scene, as McNulty beautifully describes it, to "near blinding Oedipal apotheosis.").    From Wordnik.com.  [Garrett Eisler: Bergman on Stage] Reference

Not the great sorrows of life, or its great sacrifices, but fretfulness, ignoble worries, sordid cares, are that which draw lines upon a woman's face and harshen her features.    From Wordnik.com.  [The History of Sir Richard Calmady A Romance] Reference