Well, I used this (http://www.runtimedna.com/IGD-Iron-Fist-Bundle.html) for the attached picture but the problem is that it’s a full body pose without separate hand options. Technically the image is Genesis figures but the pose set is for V4 and M4. I tend to use ironman13’s utility pose pack for a lot of things (http://www.renderosity.com/mod/bcs/utility-poses-variety-pack/80131) and that does come with various hand only options but martial arts stuff is limited since it’s a general catch all set.
Pretty easy to make a fist. i just threw this together and basically with limits on, just bend each finger digit all the way and then pose the thumb. There is a basic fighting pose for genesis male which has the right hand, as pictured in a fist.