I'm going through my first play-through of Shadow Dragon, and I was holding off on promoting Caeda because there may be an Elysian whip to promote her into a Falcoknight.
In the sequel, New Mystery of the Emblem, there's one in chapter 16, but I didn't find one in Shadow Dragon. I decided to promote her anyway but I'm curious if there was one in the first place or if it's only available in the sequel?
The Elysian Whip is available in Fire Emblem: Shadow Dragon, as well as several other games from the Fire Emblem franchise. It first appears in Fire Emblem: Shadow Dragon and the Blade of Light (1990).
In Fire Emblem: Shadow Dragon (2008) can be purchased from the online shop.
You can read more about the Elysian Whip by viewing its Wikia Page