The first, telegraphed blow is indeed blocked, and then comes that stab. He's had worse -far worse, but it's still painful; more than that, though, it's surprising, goading him into trying to back away.

While that means the pin slides right back out, it causes another twinge as it does so that distracts him yet again from whatever else she might be doing. When she rushes him again, he manages to grit out a "Fus," but the effort staggers him worse than it probably does her. He's not going to make the mistake of showing her his back, he isn't that far gone.

But then, he's worn down enough that she probably doesn't need him to.