I knew a bug would sneak through :-)
A character that is At Risk is NOT able to take a Step.
The description of the Step rule suggests that you can, which is incorrect. (Maddeningly, I did get it correct in the Conditions of the Step rule).
As a point of additional clarification, At Risk status is applied when you declare your action.
K'Erin can Step before and after Brawling.
If I Step up to an enemy, I am not At Risk (because I started my action more than 1" away) and I can take the second Step after resolving the attack.
If I am already within 1" of the enemy when I take a combat action, I am At Risk and cannot Step at all, whether before or after the attack is made.