What I did was I rode the dragon for a few hours & left stamps on my map to track it's general path, that way after I pulled the sword, I could find it again (of course there's online photo guides, but this was my personal way). It's made it super easy for me to get as many horns as I could possibly need. Also, once you have that quest, it seems to fly much lower than you'd think, usually crossing under many of the major sky-islands or over many of the towers. One last note being to get a photo that way if the dragon crosses under an island, you'll be notified if it's close by. Good luck! Honestly the parts don't feel that useful for weapon fusing to me, but yeah. Useful for cooking, though!