Talk:Hassan of Serenity/@comment-35109771-20180528202430/@comment-30468100-20180622232705

Purely my thoughts on the matter, but it's probably a passive ability that could be adeqeutely described as "Affections of the Holy Grail-Pure".

As Galahad's legend was intrensically tied to the Arthurian Holy Grail, being it's chosen bearer and the only being in the world considered pure enough to carry it, it's alluded that through him the Grail could ennact certain miracles. Notably, unlike the modern Grail (an thus the version of the skill that Irisviel's affection gives Assassin EMIYA), the Holy Grail of Arthurian Legend was a much purer entity with no corruption.

As Mashu has been bonded to Galahad, some aspects of that legend also are within her, and they materialise as a bond of protection around the Master, granting immunity to maladies of any kind (which includes poison).