It sounds like you're referring to NY!Azura, if so Hone Fliers is incredibly rare skill I recommend giving to a flying unit that you use a lot as merging dancers isn't as useful as it is for other units since they have lower bst.
If you need Hone fliers and dont have any other source of fodder ,dont. She gets +1 into hp and speed which is a valuable increase for the first merge since she favors high speed and can deal decent dmg in flier teams even though shes a dancer