You need to acquire all the skills under the Scholar Job for one of your 8 characters (Cyrus included).
If you are already aiming for the game completion and thus the fully determined weakness of every enemy, you will likely have Cyrus in your party at all times. As such, you should easily be able to save the points (or acquire more than enough Job points) to purchase even the 5k point skill awaiting you at the end.
Don't feel the need to rush this either as I was only in the early parts of Chapter 2 when I maxed out Cyrus's Scholar job.