Gishou's page

If your GM lets you take it, you should take equipment trick (rock). It would let you treat rocks as normal weapons or improvised weapons, whichever is more beneficial for you.

I think that it is a much worse thing to do to someone then kill them.
You are effectively killing them and replacing them with someone who is opposed to everything they ever stood for.

You could try taking Leadership the next time you can pick a feat and have it be your cohort.