What does Wesley's selection as Field Watcher for the only two slayers in the entire world say about the Council and it's capabilities & priorities & resources?
That he is a yes man and the Council knows what they’ll be getting by assigning him. In fact I’d wager they specifically chose someone utterly unassuming and laughable so that everyone would underestimate and write him off, making it easier for him to stick around and push their agenda (albeit unknown to himself how “used” he was).
Wesley isn’t meant to be overly competent or strong. His sole purpose is to enforce the will of the Council. Keep in mind this is the same season wherein they basically send Buffy to her death completely unaware and unarmed as a barbaric “test”, but not before their rules cause Giles to drug her into a state of helplessness over the course of several days.
Giles and Buffy have a very apparent and very different relationship than expected. He’s less of a mentor than he is a father figure, and for them, that’s dangerous. The Slayer line is literally predicated on the idea of control, with Sineya being a vessel used by an external group to exert their beliefs and will. Giles is very obviously edging towards the territory of being able to say “no”, and with Kendra dead, their chances of reassuming control of the situation are slim to none.
Enter Faith, who just lost her Watcher and is looking for guidance and purpose. She’s capable, as good if not better than Buffy, and is dangerous. Relocate her and Wesley to Sunnydale as a backup plan, and there we go. Now if either (or both) the primary Slayer or Watcher go rogue and become a problem, we have an option.
With Faith and Wes around, the Council has a chance they’ve never had before: they get to be picky. If Buffy doesn’t do what they want, they always have the backup, and if Giles forgoes their advice/statutes, they have an agent who is all too willing to be an unwitting pawn. They didn’t account for Faith’s fragile mental state, thus sort of ending their behind the scenes scheming. But Wesley being sent there was 100% a way for the Council to have an inside man who would ensure that their goals and plans came first and foremost.