Tidus can see the slips, the hesitance, the show that he's getting through, if not entirely. But even a little is good! A little is what he can worm his way into, especially with how Inigo agrees with him.

Nevermind the 'but'. The but is the barrier they need to push past. The reason for the squeeze to Inigo's shoulder, the passion to Inigo's low-spoken voice.

"Sometimes," he says, "you can't go in gently. You need to go for it, a leap - and it's scary and it makes your heart go crazy, but you do it! Then, you see that you can. And that feeling, after the fear? That's what sticks with you."

That you did it, that you won't be held back; that you can do a lot more than your anxiety tells you you can't.