Right, I forgot about our general rule with women Viserys finds attractive.
Attractive? She has neither horns, nor wings, nor any other monstrous feature. What about her is Viserys supposed to find attractive?
In all seriousness, I see no reason to deny the proposal. While most of the Planetos aristocracy has been rather disappointing in intellect and survival instincts, we've also had plenty of examples of the opposite. It seems only fitting that the true power behind the Glassmaker's guild be somebody not only competent and ambitious, but also open-minded enough to find opportunities in danger. Danger like a Dragon who dislikes everything your culture stands for, and very much would like to conquer your city... after which he would need competent administrators and underlings.
I think we've learned a few valuable things about her.
1) She has reliable access to high level mage : The item on her was not merely bought. She knows about teleportation and recognized true-sight, implying a high degree of familiarity with magic.
2) She is likely the mage in question, or high level herself: She was very confident and controlled during the conversation. Viserys was also unable to pick up much through Sense Motive. She also made it up to the highest echelons of Myrish society. At the very least she must be beyond your typical NPCs level 5 restriction.
3) She has access to regular divination: Her comment about the luxury market seems highly indicative about her being aware of the creation of our newest business venture,
Tyene's SecretTM. This seems like something you'd need quite a bunch of pointed questions for to discover, which implies that she has access to quite a number of questions if she can waste them on something like figuring where new competition comes from. This also makes the theory of a high-level mage more likely, since they'd have access to more questions per casting. Either that or a larger number of mages to share the exp cost.
and lastly 4) Of the remaining leadership,
none possess any magic or magical items whatsoever. We've seen in multiple cities already that people are not stupid and will try to get some magic themselves after witnessing it. The exception to this has always been when somebody already had a monopoly on magic and was making sure that magic stayed in the shadows (e.g Lys, Pentos). I suspect that she either has close ties to, or is herself the local kingpin of magic.