In P6 you can do a pretty good job with waves and magnets.  The "victim" object needs to have a fairly dense mesh so the deformers can move the surface in detail. 

First: Animate the "weapon" and "victim" to form the hit.

Second: Add a magnet to the "weapon", and set the magnet's Objects Affected pulldown to include the "victim" object.  Then play around with the magnet and its zone until it makes a good dent in the "victim" as the "weapon" approaches.

Third:  Add a wave to the "victim", and play around with the wave and its zone until it shows the kind of ripples you want.  Animate the Phase and Amplitude so the ripples begin just after impact and fade out shortly thereafter.

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