First thing's first: my apologies for not quoting where necessary, as my old mobile isn't giving me an easy life as it is. Also, this information and criticism is important, I hope you guys keep me, and the OP, (and anyone else who wants to help) on our toes, for as long as you help us make the 5e Binder worthy of the name "Pact Magic"

Even though Anaximander won't be back for a few more days, I'm planning some suggestions on how the OP could improve the class model. Among them is a change on how many vestiges you can have bound at a given level, and talk about making adjustments to the vestige template that might be less "1 size fits all". I aim for it to be a step in the right direction.

@Naberius - Frankly, I don't know for certain either what skills the Binder would have. So I work with guessing. But it's not an intended implication about me wanting the binder to be skill-heavy (at least not at this point) but an observation in the current design - the options for passive abilities include skill proficiencies. And I point out that it can get pretty messy as we go along. My current thoughts at this point involve offering advantage on thematically appropriate checks. In Paimon's example, I don't feel at ease adding an increase to dexterity or handing out skills. Instead, I may start giving the dancer theme in the form of a free ribbon, and might look something like this:
Quote Originally Posted by Paimon
While wielding a finesse weapon*, You have advantage on all Dexterity (Acrobatics) and Charisma (Performance) checks made to dance, tumble or whirl.
I'm still working on Paimon, He's not as easy as I thought, since his signature dance (move+attack everyone you move past) is something any melee-fighting character can already do in 5e. I'm currently trying to think up an innovative solution with him.

Finally, if you have suggestions or comments on what I could do to improve the vestige, I'm all ears.