A white dragonborn (or someone who appeared as a white dragonborn) bought the dagger. Also a white dragon was suggested as a possible explanation for Selwyn's death, but presumably that would also apply to a white dragonborn's breath weapon as JandK says. Also, we now hear the dead dragonborn was also a white dragonborn, though he clearly couldn't have killed Selwyn. We also have a name - Crane - as the person the Sorcerous Sundries proprietor seemed to think might be selling the dagger. The dead dragonborn was called Julikar Caeziryn - if the "family member" is to be believed. In fact, are we sure that the dead dragonborn was in fact white, or do we only have the word of the "family member" and was the descaling to disguise the fact he wasn't white? Because, erm, reasons. We also have a number of murders that involve great strength and/or magic and a dagger that requires sorcery to attune. A dragonborn, with high str and cha, could well make a good suspect. Plus there's the bloody dragonborn handprint near Drusilla's, which sounds like it might have been left by someone who had just killed a bard with an anchor, run towards Drusilla's (per original bloody footprint) then made their escape down the tunnels ... towards Riverveins?
The Guild have also cropped up again and rituals, though I couldn't work out how Magpie and the Guild member taking people under their wing was related to the Riverveins rituals that weren't, according to Drusilla, what they seemed.
We also have either an inside job or impersonation involved in Selwyn's killing - obviously Rourke is a suspect if the former, but possible impersonation has popped up a number of times in this case.
And the victim at Insight Park confirmed as Felsom Felgrim, so not E Shearan. Why were we given that latter name when we first visited the morgue? I started to wonder if I'd misinterpreted the situation, and E Shearan was the name on the bard's toe tag, but it definitely says E Shearan was under burlap and the bard under a thin sheet. Hmm.
Also, Felgrim killed by magical thorns (so Entangle, Spike Growth or Plant Growth?) not a dagger, so only connection to the dragonborn now is the note signed Grom, the gravedigger at the site where we assume the wrapping for the dragonborn corpse came from plus, as pointed out by Lyelle, the gravedigger's suspicious behaviour in preventing asking any more questions of the dragonborn. Otherwise, it's feeling quite different from the murders of the bard, butcher and Selwyn as I don't see any connection to a possible white dragonborn sorceror.
Also, I think we can take Fel confirmed as Top Hat aka The Butler given the similar speech mannerisms? Did his description sound like a redcap to anyone else? But another talisman has been lost, grr!
Need to mull this one over a while before deciding where to go next.
"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"
