I personally would rehab him in the frag tank for a month or so. Get him fully healed, eating well, his strength back up, etc. before trying him again in the DT. This way your other wrasses don't sense any "weakness" from him, and if he does get attacked again he will be in better shape to defend himself and/or survive the onslaught.
One downside to having healthy fish is they *HATE* weak, sick fish and will deal with such fish in a brutal manner. I once returned a goby to my DT that wasn't 100%, and even my little sissy fish tore him apart.