I'd rather be a skier than a boarder in those situations. If things got going bad you have four weapons to use (poles and skis). I'd use the pole first, skis could kill someone if you use the edges. But that's just if you have no help and no one is coming to break it up and that person is meaning to kill you.
You would NEVER, EVER use a piece of equipment if you were to get into a fight- you're dealing with some serious assault/battery with a weapon charges, which mean jail time. If you're smart, you try to end it as quickly as possible without throwing blows- wrestling the guy to the ground, using friends to restrain, etc.
unfortunately ive hit someone with a skidoo helmet before. we were being towed behind the snowmobile on gts and he jumped off of his gt and landed on me, sent me flying head first into snow, i was freezing fromt he snow down my coat. took of my helmet in like .5 seconds and smashed it across his head. i felt bad after but im pretty sure he deserved it. since i think i could have seriously hurt my head/neck at 50 mph into the ground.