The Frenchman has not played for the Blades since July due to injury.
Asked about the winger's recovery, Wilder replied: "Lys is looking well.
"I'm not sure his gear is to my taste, not the stuff I've just seen him wearing in the corridor. Obviously it will have cost a number, because that's the way it is these days. But you won't catch me wearing it.
"Lys' attitude and personality lifts everybody. He's a good lad with a bit of an aura around him. They are huge players for us."