I wouldn't really worry about strengthening wrists/forearms seperately. Just work deadlifts or bent-over rows, you'll get good effect from that. I also used to do pinch-grip lifts carrying weight plates up and down the stairs in my house, which was useful for my BJJ stuff (we train in gi).
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin