To ravage is to bring heavy destruction, to devastate, or to pillage. The meaning of ravaging is straightforward, as it descends literally from this main sense of ravage.
Ravishing is trickier. Ravish has two main meanings: (1) to abduct and rape, and (2) to enrapture. Ravishing extends from the positive second sense—it means, essentially, very attractive—and is generally not associated with the negative first sense, so it is unfit as a synonym of rape. Meanwhile, the form is best confined to its participial adjective sense. As a verb—e.g., he was ravishing her—it is easily misinterpreted.
But as the flood waters continue to ravage the countryside, attention has now been focused on the economic turmoil. [Smart Company]
Couple this with a war that continues to ravage the country and you would be hard-pressed to find anyone in Afghanistan who was feeling relaxed. [Cincinnati.com]
Despite its good young cast (including the ravishing Liv Tyler as a reformed hooker and addict) the film was panned by critics, somewhat unfairly. [The Guardian]
He created his ravishing images—often sexual, sometimes tragic—by pushing paint over a canvas, sometimes very large canvases, at a time when painting on canvas was still pretty new. [NPR]