User blog comment:Valeth/Random Musings - Did Lore Segregation happened on FGO Gacha?/@comment-33628324-20181201193612/@comment-27971189-20181201200101

Yeah, I'm kinda confused with some of it too, hence Cu and Proto Cu, also Ozy and other former Proto Servants knowing Arthur example.

Other than it would be Semiramis. Semiramis should be able to be summoned normally (unless the reason is she come with complete set of Hanging Garden, which indeed violating her normal summoning result)

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For Sigurd, I think the reason is because Siegfied recorded first as his bond data said 'he is considered as same but different entity to Siegfried.

If that's the reason, then Bryn being Limited most likely because its Brynhildr from Sigurd story, not Brynhildr from Siegfried story. It could be Chaldea database recognized Nibelungenlied but Volsunga Saga thus Sigurd and Bryn are Limited.

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As for the strong, I don't know who is other Servants as good example. Even without Grand status, I can't see usual magus ever managed on summoning King Hassan.

Meanwhile, Gil himself is very conscious about his strength, I mean he summoning himself, even participating in last battle against Goetia following his own will is something else.

I didn't know if we once got another example other than them.