Q:

Arity exception deref'ing promise

I'm using the http-kit library to make some webcalls and it returns a promise for each.  
When I try to deref any of the promises in the vector I get the following error
ArityException Wrong number of args (1) passed to: core/eval5473/fn--5474  clojure.lang. AFn.throwArity (AFn.ja
va:429)
Simplest way to reproduce in a repl without http-kit is as follows
Create collection
(def x [ [1 (promise)] [2 (promise)] [3 (promise)]])

Simple Test
(map first x)
;user=>  (1 2 3)

My Test
(map #(vector % @%2) x)
;user=> ArityException Wrong number of args (1) passed to: user/eval109/fn--110  clojure.lang. AFn.throwArity (AFn.java
:429)

Update
I should probably delete this question.  The problem had nothing to do with promises as Valentin noted below. 
I was typing %2 and thinking second argument.  When what i needed was @(second %).  i.e second entry in first and only argument. 

A:

The function that is the second argument of map must accept only 1 argument in this case (which is meant to be an element of the seq that is being walked through). 
You seem to be mistaking passing 2 arguments to a function and passing 1 argument that is a vector of 2 elements. 
What you want to write is
(map (fn [[a b]] (vector a @b)) x)

...whereas what you're currently writing is equivalent to:
(map (fn [a b] (vector a @b)) x)

So this is not a problem about promises in fact.