Concerning a good deed done to an impotent man (epi euergesiāi anthrōpou asthenous). Objective genitive. Note euergesia (old word, in the N.T. only here and 1Ti 6:2), as a benefactor, not a malefactor. Skilful turn made by Peter.
Is made whole (sesōstai). Perfect passive indicative of sōzō, stands whole.