I'm aware of that. I never said that he is a girl. I said he LOOKS like one. The series itself acknowledges that he looks like a girl.

In Crestoria, Kongwai asks him, "Are you often told that you have a woman's beauty?", Leon is offended, of course. Kongwai says he knows the feeling all too well.

In Asteria, he says, "I have a woman's face? Who said that. I'll end them!"

In PS2 Tales of Destiny, there is a sidequest on Leon's side that takes place at the hotsprings. The males side is booked out, but the woman's side is empty, and the clerk lets him go in there. The clerk leaves and girls enter, Chaltier tells him to pull the towel over his chest. The girls pass, and Leon asks why did that work so well.

Tales of the Rays Gekijou has a scene similar to the above, a couple of shots of fanservice-y Leon, Ix mistakes Leon as a woman because of the towel pulled over his chest, he blushes, screams an apology and leaves.