Spirit of the Storm Lord requires you to get to the last stage of the Isle of Thunder (well that was obviously done a long while ago now).
Once you have unlocked the final courtyard you need to thrust the Lightning Lance into Nalak and survive long enough for it to be tempered.
I wowheaded the quest and fond that it was best to go to the northern steps, thrust the lance and then run north away from him.
This I did, but walked backwards for too long before just turning round and running so I took a big hit to the face.
I then ran around kiting the ad whilst all the NPCs fought Nalak and then I died just as I got the tempered item - woot!
Off for another chat with Anduin and the Black Prince...