Sturdy Horseshoe WoW is an item you'll need if you're trying to get the mount Sinrunner Blanchy in Revendreth. Here's where to find some Sturdy Horseshoe and how to unlock the mount.
Sturdy Horseshoe WoW: Where to Get
To get Sinrunner Blanchy, you'll need to find Dead Blanchy at Endmire, north of Darkhaven, and bring items to her. She's sickly and frail (and also dead), so you'll have to nurse her back to the dead horse equivalent of good health to earn her loyalty and trust. Each day you'll have to give her a different item, and after six days of doing this, you'll get Blanchy's Reins to get the mount.
It's a daily quest, so you must visit her every day for six days to get the mount. You can do this in advance by grabbing all the items you need before the quest starts. The items can all be found scattered about Darkhaven.
The third day has you get Sturdy Horseshoe for her. You'll need four of these, and you can get them by interacting with Discard Horseshoes on the roads that connect Darkhaven and Endmire. Check out this video by WoW Quests for exact locations on where to find them.
The Horseshoes will respawn fairly quickly, so you can go back and forth between two known locations to get the four you need quickly.
Besides the four Sturdy Horseshoe, you'll also need eight Handful of Oats, a Grooming Brush, a Bucket of Clean Water, a Comfortable Saddle and three Dread Hollow Apple. Give her all of these and you'll earn a horse companion for life (and death).