Better yet, we'll go through it all at once and I'll give you everything said by / about him.
Gods' Grip
After Reyner triggers the Echo in which you see Sthalmann vow to arrest Y'shtola, you head to the Gods' Grip, as well. However, there you find only Blackburn, who apparently fishes here in his spare time, as do Sisipu and Rostnsthalmann
Immediately after he says this, WHOOSH, Y'shtola is standing behind The Player and says, "Be warned, adventurer. Blood will be spilled this day." Sthalmann arrives, angry that she has broken their deal to meet alone (because The Player is there), but she claims that she has no control over the whims of an errant soul, and the scene plays out as if The Player wasn't standing there until the middle of Sthalmann v. Y'shtola's fight (during which she displays some insane superpowers - vaporizing a bullet in midair, blocking an axe swing with her palm).Originally Posted by Blackburn
The Key (horn) glows, and another Echo is triggered (despite already being inside of one seemingly generated by Blackburn). Immediately, Y'shtola expresses her confusion ("What is this place? Where is Sthalmann?"), which leads me to believe that every time The Player has seen her prior to this, she was in her own real-time. In this Echo, you watch from afar as Sthalmann, Emerick, and Merodaulyn lay out the initial plan for their scheme. Afterwards, both you and Y'shtola are thrown backwards by nothingness, and Y'shtola is shocked (The Echo... You have been touched by- You can walk the warrens of the past!), which implies that you did this, somehow, not she. The way she cuts herself off there also implies she knows what we're touched by to some degree. (FINISH YOUR SENTENCES, CAT. TOUCHED BY WHAT? WAS IT SIREN!? I SWEAR TO TWELVE IF IT WAS SIREN...)
This may fit your "Did you change anything about the past?" to some degree; it's possible that, if you truly were the one that triggered the Sthalmann Schemes Echo, then Y'shtola would not have seen it without you there, thus she would not know Sthalmann was the enemy, and thus wouldn't report him to the Knights of the Barracuda. It's possible that this is what caused him to fall from power. Holy hachimaki; talk about a time-loop paradox! This is the first time I've interpreted it this way, so I may be missing something - or I may be onto something. Either way, it may fit the bill for what you're asking for.
After the Sthalmann Schemes Echo, a starshower hits and Travanchet appears. During this starshower, the camera follows one sparkle in particular; to me this implies that Travanchet rode the starshower in - but that's not gospel. He might have just appeared from shadow and the starshower was an ill-omen, as the journal implies. Who knows? Either way, he takes the key and jets.
As I said, it's possible that, if you weren't there, Travanchet would have stolen the key and Sthalmann would have undermined Y'shtola and taken the Admiralty, somehow... so that's open for debate. After Travanchet disappears, you pass out entirely, and Blackburn says...
The Player wakes up back at the Mizzenmast Inn under the care of Baderon, a mutual friend of The Player and Blackburn. All he has to say about the matter is:Originally Posted by Blackburn
Arrival at the Walking SandsOriginally Posted by Baderon
He leaves, you talk to Minfilia, who gives you a generic rundown with his namedrop (I assume the phrase is exactly the same with other namedrops in other cities).Originally Posted by Blackburn
Originally Posted by Minfilia
UNLESS...
Originally Posted by Blackburn
. . .
. . .
. . .
BOOOOOM!
Emerick, as in emery - a mineral that is dark gray and used as an abrasive.
Dark gray as in BLACK, abrasive as in BURN.
THAT'S why he knows the fishing spot,
THAT'S why he's able to trigger the Sthalmann echo,
AND THAT EXPLAINS THE ABRASION. ON. YOUR. PAAAAALM.
It doesn't answer any of my questions, but still.