Arm-impaired rowers are going to have to sweep in some fashion…either in a supported “Scull Pair” (rowing with a single scull blade in one hand), or in a conventional sweep. But for the latter, one really needs a way to connect the sweep blade to the impaired arm side to provide the control and balanced pressure from the both because (a) the larger blade takes two contact points to control really, and (b) so as to not exert too much side torque on the torso.
Sometimes that adaptation is as simple as an ActiveHand grip if the impairment is mere weakness. But when part of the arm is missing, a more sophisticated (and often creative) connection is necessitated. Many single-arm rowers own various prosthetics for their arm, but often these are not designed to support the degrees of freedom that the rotation of the blade introduces.
Single-arm Marlow rower Emily Whitley jettisoned her conventional prosthetic and fashioned her own custom attachment using a strap for securing a motorcycle and a weight training band. The use of a completely flexible band (as opposed to a semi-fixed mechanical device) provided all of the motion required and comfortably allows her to exert balanced blade/torso pressure.