"Sure. Actually, doing it together might be a good idea."

Because Inigo would feel kind of lame demonstrating on his own. Even back home he often practiced by sparring with Owain, rather than practicing moves by himself.. And if Tidus is offering, then he may as well take him up on said offer! (He's.. definitely a bit nervous about demonstrating it in front of someone he doesn't know well though, but--!! He know he can't let his shyness win here, he'll miss out on a good opportunity!)

He summons his sword from his band, holding it at ready.

"Come on, Tidus, you swing the first hit. I'll try to show off a little so she can see."