He says that Morrolan's friend of the Old People should know about Spellbreaker/Godslayer. He is obviously referring to Vlad as being of the Old People—much to Vlad's confusion. However, we may infer that a Serioli term for Easterners is 'the Old People'.
We know, from Sethra Lavode, that the Easterners predate the Dragaerans, and came from some other world. Presumably the Serioli retain this knowledge as well, even if the Easterners themselves have lost it, and the term "Old People" references the Easterners' ancientness. By the same token the "small invisible lights" may refer to the other planet(s) the Easterners came from.
- See also Speculation:Old People.