Immune system is also capable to memorize the things it encountered, which also can be applied. Like, a mystery which allows Levi to gain resistance to already encountered spells. (Stupidly useful for farming mobs)
question that hit me in the middle of writing this: When servant's die their souls go into the lesser grail (in this case Ilya). but if ilya is still here, it means she never "went full-grail". which implies that even if this is one of the "Shinji-grail" timelines (im sorry, im getting multiversally confused) that whoever got stuck inside ilya, didnt get into the grail...
so is Berserker still stuck in Ilya's body? or if not then where did that soul go?
Basically: In every timeline to my knowledge, either Ilya, Shinji or Sakura goes "full grail" but at least one of the others has a servant soul stored in their body, that at the end of the story is left unaccounted for. What effects does such a soul-embedding have on someone over time?
Thinking about closest known analogous situations there have to be SOME effects though.
those two analogous situations are: Shirou and Sakura.
Shirou has a Noble Phantasm embedded in his soul (avalon) for a 10 year period, and ends up absorbing a lot of its properties into himself. note that avalon had 3 purposes:
Holding weapons within itself.
moving objects from one layer of reality, into another.
all of which are traits that shirou has in extremity.
and sakura, who has the whole "Dark Sakura" thing going on.
so with that in mind: What about Ilya, which servants and NP's are inside her now? and what would their effects be on a greater timeline.
Is God Hand Berserker's only noble phantasm, or merely the only one SHOWN? what happened to the soul of Gilgamesh (did he die in fate? its been a while)