He was supposed to be their Bond, but he worked directly for Maeve most of the time. That's how he ended up turning traitor. He was even worse at his job than she is hers.
He was a meat head that Maeve kept around, and Mab didn't replace him on the spot because she was scouting people worth the effort to replace him.
This isnt true.
Nowhere is it suggested that he was actually bad at his job. Not up to Mab's standards, perhaps, but bad at the job?
Not at all true.
Slate successfully assassinated Reuel without leaving a trace.
And Reuel was an old Summer Knight, who grew old in the job, with everything that implies for his competence, experience and luck. You dont pull off shit like that by counting bottle caps.
The knight is a tool for the winter queens, and this particular knight was a blunt instrument. He probably got less than Dresden does, and Winter wasn't exactly open to him in canon.
You're also basically asking for him to pump him for information on Winter specifically, which arguably runs into one of the clauses that restrict our favor.
Either I'm right and he's worse than worthless, or you're right and trading him away would be a strategic problem for Winter. Not a good ask when he specifically isn't necessary for anything we're trying to do.
It's not like it's beyond our capabilities to become friends/trading partners with some Sidhe on either side of the line and get what we want that way.
None of this is true either.
Dresden has been deliberately avoiding playing with the Sidhe power structure, and is aloof at best.
Slate, on the other hand, had the connects to intrigue with the Summer Lady right under Winter's nose.
That takes serious chops.
We're not interested in him for information on Winter.
We're interested in him for information
on what Winter knew about other major factions and threats as of four years ago. Its the equivalent of getting a look at the CIA/NSA's classified files on Russia/China/the EU as a newly independent nation.
As for schmoozing other people?
We had it explicitly demonstrated in Dead Beat that Winter's command structure has varying levels of information access.
When Dresden tried to summon Lea for information on the Kemmlerites but got Mab, Mab gave him information that Lea would have had by job and experience.
Not all the information that Winter had available, or that other people would have had for their jobs.
Man's the only source on the market.
He's not all access, but by the nature of his job, he had to have pretty high access to do it right.
1. Winter and Summer are balanced, so much so even the little power that resides in the Mantles of the Knights will change it. But the power inherent to the Mantle doesn't mean the Knights themselves are powerful; Dresden is powerful because he's a wizard who knows how to handle such a power source, while no random Knight has ever been shown or said to be equal to a wizard in any way.
2. Slate was an idiot. That he believed something stupid should not be a surprise, and we should not believe him.
1) Its not little. Ask the city of Milwaukee.
Many a Knight has no extraenous power source the way a wizard Knight like Dresden does, yet the Mantle of Knight provides enough grunt to make them a seriousface threat anyway. And they do get training in how to use it from their Court.
There's a significant amount of power there. Its just seldom necessary to have a Knight that can use all of it.
When Winter Knight Dresden fought Summer Knight Fix in Cold Days, he didnt overpower him.
He beat him because he had more combat experience.
And because it was Demonreach, where he had Intellectus on his side.
2)Slate wasnt an idiot.
A drug user, sure, but that doesnt actually make you stupid, any more than Shagnasty's murderous habits make him an imbecile. He's no Dresden, but he didnt have to be to do the job that was needed at the time.
