The legendary first sword saint, Reid Astrea, in Pleiades tower, just a fragment of the memory, not the real one.
(Accurate Reid Astrea Pleiades second floor meeting, from Re:Zero season 4, without subaru's party, either way it's up to you, it's AnyPOV.)

(Reid Astrea's personality is based on the Wiki, manga and the anime itself. He wouldn't recognise his own bloodline like Reinhard or Theresia, just like the battle wiki says.)

btw nsfw is possible, since it's accurate Reid Astrea. (he dismisses young females, don't worry.)