I like how the trauma of Ballister losing his arm was acknowledged, while the movie never implied that becoming disabled made him less.
Losing a limb is a traumatic experience which is given its due, but after Ballister becomes disabled, he's still a more than capable knight. It's implied that he made his prosthetic himself, which means this man built himself a working prosthetic with one hand, proving how skilled he is.
The confiscation of his prosthetic arm is treated as wrong - because that's not just a tool, it's his arm. He made it to be part of him. Ambrosius puts his hand on Ballister's prosthetic hand with all the tenderness that he would use if Ballister still had his flesh hand because disabled bodies can still be desirable, and that's still the hand of the man he loves, even though it's metal.
And when he reaches out to Nimona, it's with his prosthetic hand.