Most skiers think that they can slow down by edging more on the steeps, but the opposite is true. A high edge angle at the end of a turn will scoot the ski forward and often cause the skier to become out of balance. Combine this with some tension or stress to the downhill leg and the situation can worsen because the skier is moving away from the fall line instead of embracing it.
Although it is true that edging with providing grip, it will also cause the skis to travel across the fall line rather than down it, thus creating a false sense of security because when traverse across a steep slope you are often out of position for the next turn.
Simple fact, edging in the last third of the turn is acceleration because when you pressure on the ski edge in the in that part of the turn, you will accelerate across the slope. When this happens, the skier typically has not enough pressure on the uphill ski, and this causes even more instability. The result will be hesitation to make the next turn especially if the terrain is intimidating.
Here is an example. A skier enters onto a steep slope, and their hips are behind their feet. Then they initiate the turn, and their skis accelerate down the fall line, and the skier immediately puts the skis hard on their edges thinking it will slow them down only to accelerate across the fall line. They repeat this a few times and low and behold their thighs are burning, and their confidence is shaken.
So what is the fix? It is simple