Wrist protectors a must.
I've been working in the ski industry for 30 + years. The first five of it patrolling. Wrist injury's are probably the most common injury for snowboarders, and yet even today most riders don't wear wrist protectors. Almost all ski hills today make it manditory to have a helmet to ride their parks but you'll still see plenty of riders on the slopes with no lid. Crazy.
As far as other types of armour go, nothing wrong with that but don't feel like your ass is completely covered. Spinal injuries from skiing are a different mechanic from what might occur on a bike. With a bike you have much higher velocities and a generally flat trajectory. So when the impact comes (curb, guard rail, tree) good armour is your only friend.
On the slopes you can have these same types of trajectories but at much slower speeds, hence less severity. What does become severe at lower speeds is when you change the trajectory. Catch a little air and your trajectory is no longer flat. It's a parabolic acr and the impact zone is the run, not a tree or light standard or whatever. Landing flat on your back is going to hurt like hell but you'll most likely walk away from it. Land at an angle on your but or worse your shoulder blades and the spine compresses and sometimes hinges. Unfortunately back armour won't help. Also unfortunate is that this is the pre dominate type of spine injury on the slopes or in the parks.
To the OP
I hope your friend has recovered. I really feel that helmets are still what's need in the sport. Cool ones that the little guys will want to wear and force their parents to buy. It needs to be driven at that level.
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