When writing a job specification there are various things that you have to take into account.  It should outline the key responsibilities and duties that the role involves.  When asked to make a list of requirements, it is natural to put down everything we can think of and almost every employer will fall into this trap. 

This is called a wish list, obviously putting down all the things that we wish for in the perfect candidate.  A person with all of these criteria will invariably never exist because we are asking for the perfect person.

What you need to do is look at the role with its duties and responsibilities and give them a percentage break down for what they will be doing in a typical day and in order of importance.  This will then allow you to identify what are the key and most important aspects of the role to consistently attract the right candidates.