So, frankly, all of this is terrible. But there's three things Lucien just learned from the book, if the book is true:

1) There are traps here that can be set off, at least one of them on the staircase involving a "holy pie".
2) The other person in the Spire [i]would have assisted in his funeral.[/i] At the very least, that means [i]they would be a friend.[/i] 
3) That would make Jackdaw the "Drowned Seeker" - Implying she'd survive this. 

"IF"; Lucien's suitably paranoid to wonder if the book itself is the trap. There's one way to test it, at least: Find the trap it predicted would have killed him, and don't get killed by it. 

If it's as the book says, he can infer the "Grail Questor" is probably going to be a friend, and that there's a chance to save at least a part of Jackdaw. Also, whatever a 'holy pie' is, it sounds like the sort of thing that'd be a lot more effective against the undead(?) crab monster downstairs than his waterlogged revolver. 

Find the trap = don't die to the trap = aim the trap at big crab monster = trust the book = trust the other person here is an ally, not another enemy = save Jackdaw. 

Terrible as things are, that's still a [i]hell of a lot to be hopeful for.[/i] 

[Look Closely - 3, 4, +2 = 9]

"Is there something hidden or out of place" - Looking for hidden traps
"What will happen if I try to set the trap against the Wreck?"
Tell me more about the scenery here - the squid statues, the gigantic and overstuffed shelves of books. How could they help me? How could they hurt me? Essentially - If the trap idea's a bust, is there an [i]even bigger bust[/i] that I'd be able to drop on the Wreck? A [i]spire[/i] implies a lot of height, and everything you've been describing sounds tippable and heavy. 

I find one of these things out the hard way.