I have written many articles in the past about balancing and most people think standing balancing exercises when the word balance comes in to mind. You can still work on balancing your upper body with various exercises. One of my favorite upper body exercises to challenge my upper body balancing skills and my wrists are push ups on rings.
The idea is very simple. You basically use two gymnastic rings to do push ups on the ground. You will try keeping the rings perpendicular to the ground at all times. On early stages if this is too difficult to do push ups in this position you may want to do planks holds in this position. This can help with building up the necessary wrist strength that you will need for doing push ups in this position. You can also vary the distance from the ground while you do these plank/frozen-push up holds prior to moving on ring push ups.
I rarely isolate and work on wrist exercises such as bicep curt, wrist hammer rotations, etc. I use exercises like this that work in conjunction with other muscle groups just as they will be working during a combat situation. This type of training will improve your pushing power.
In order to have a stronger grip, it is a prerequisite to have a strong wrist. Many of the grip specialist spend tremendous amounts of time working on their wrist strength in order to improve their grip strength. This exercise is not just great for strikers but for grapplers who need stronger wrists to have establish a biomechanicaly strong foundation for grip strength. Aikido practitioners and wushu practitioners can also benefit from this type of training.