After all that work, you STILL hand the crown over... Probably would have had to take it in a few sizes anyway, after having been on an Ogre's head...
All that remains is to deliver the Crown of Will to Sharlindra in the Undercity. She will see that it is delivered to Lady Sylvanas. I would warn you against thinking to use it for your own purposes, <name>, Mug'Thol's fate should be illustration enough.
So this is the relic the ogre used to duck the will of the Dark Lady...
Strange that something so simple could wield so great a power. And to fall into as clumsy hands as those. Well done, <name>, I will deliver the crown to Lady Sylvanas, and see that she hears of your accomplishment.