Minor correction, UBW does nothing to patch Shirou back up, when it manifests in the Fate route all it does is replace everything beneath his skin with swords, it prevents damage rather than patch it up.
Avalon, the ever-distant utopia, sheath for Excalibur, is what patches him up. It's the only reason he survives long enough to take part in the grail war in the first place.
Avalon, the ever-distant utopia, sheath for Excalibur, is what patches him up. It's the only reason he survives long enough to take part in the grail war in the first place.