We need video.
You need to get the forward half of the inside edge of your outside ski engaged in the snow before the skis reach the fall line. This is important. There is no way to finish a turn right if it isn't started right. On the steeps it is essential to start the carve in the first third of the turn (well, essential in all carved turns, but you can't cheat on this in the steeps). Your body needs to be downhill of your edges immediately after the transition to get the inside edges gripping the snow and carving.
My feeling is that good arm position rarely does much good, but poor arm position can do much harm. From the feet up--your feet need to be behind you so the tips are pressured, and the steeper it is, the more tip pressure is needed to start. Also, more tip pressure makes for tighter turns. You need the skis on edge as I've described with your new inside ankle strongly inverting that foot an instant before the transition and more as the turn progresses. You need your hips turned toward the outside of the turn as early as possible in the turn. This helps the ski tails grip the snow. You need to carefully modulate the edge angle and tip pressure to maintain the carve without skidding or chattering. You need your inside pole/hand/arm/shoulder/hip high and forward, and your outside pole/hand/arm/shoulder/hip low and back. As you get into the middle and last third of the turn you can allow your skis to come slightly forward so your weight is centered over your feet, never with your weight on your heels.