Martial arts training makes you better at beating people up at close range. This is a given regardless of the setting. It is also a given that it won't help you with anything else, other than via the strength, agility, stamina, and coordination gained from the actual training and practice.
Knowing a martial art or two should merely be a part of this guy's arsenal, not his sole gimmick. Other useful skills are subterfuge, diplomacy, firearms training, and information warfare.
EDIT: Regarding the knocking over, probably not, unless he's heavier than the Mini-Mecha
/power-armoured behemoth in question, or it has very
poor balance. That's probably where you'd want to start calling in support/using the environment to your advantage.
As some advice, try watching the Bourne series for a nice depiction of a brutally efficient Badass Normal
edited 29th Sep '10 6:48:57 PM by Iaculus