Ah, I can tell just by lookin' at ya -- you be wantin' to make a lucky charm. Mau'ari always knows!
To da south. you'll find a canyon, an' giants made a' solid ice. The giants sometimes be carryin' dem, but ya can always gather da shards yerself from da canyon. These shards have a powerful reflective quality.
Bring back 10 frostmaul shards, and my lucky charm will be yours.
Bring back da shards, and I be tellin' you more!
Ahh, yes... I will make da charm for ya now. Just you wait!
- 9550 XP
Follow the road south out from Everlook. Eventually you go over a bridge.
The elite 59/60 giants around and under the bridge drop the crystals. Also, though, there are crystals standing around for the taking, both in the canyon and on the lip around it. If you can fear the nearby giants, or they simply wander far enough away, you can loot the crystals without fighting the giants.
The entrance to the canyon is to the west. (Coords: 59,62)
Even though the quest description tells you to get ten shards, you only need four. Before Patch 2.3.0, ten shards were required, obviously Blizzard changed the quest objective but forgot to change the description.
As of 2.3.4 the quest text reads correctly that you need 4 shards instead of 10.