I felt Ren after removing the mask doesn't look fearsome. It in fact weakens him when confronting Rey.

Snok looks like some Lord Voldemort and wont be surprised if we bring in Lego expanded universe there. Harry potter comes in lol

I am sure Luke could have taken Ren out, but because he is Han's and Leia's son, he didn't. Whatever Rey relation is, she has less compassion and was willing to take K Ren out after what he did to Han which I bet Luke couldn't do.