It's just a theory, but... well, if it's something your body is doing because of whatever's going on today, then it's only something you can undo.
Close your eyes, Euphie. [ Waits for that to happen before he continues. ]
For Esper powers to work, the body has to generate a certain kind of energy, but the mind also has to focus that into the form that the Esper wants. Long story short, it's called "Personal Reality" -- the reality that you, as the user, want to bring into being. [ Though he sounds like he's reciting this from a textbook, he should sound pretty believable since it's close to what he was taught. ]
In this case, though, all you want to do is to get rid of this... shield or shell or whatever you have, right? So... picture it in your head. Visualize it. [ A beat. ] Once you've got hold of that image, reach out your hand. [ Brings up his right hand, but doesn't touch the barrier just yet. ]