Dragon Slayer would be a pretty cool attack, if you ask me. Though, similarly to psychic, fairy-type has some sort of mystique surrounding itself, which doesn't seem to go well with aggression and whatnot, which, I believe, is being promoted by the name Dragon Slayer. If it were to be turned into an actual move, I could more or less imagine it to be fighting. If they'd like it to be super-effective against dragon, then perhaps they'd be able to have this attack be dragon-type instead.
Another option that comes to mind is dual-type; if they wish, perhaps they could make Dragon Slayer be two, separate types at once, with one being primary and other secondary, sort of like Hawlucha's signature move. Anyhow, I'm going a little too off-topic here, haha.
If we'd like some physical fairy-type attack, I feel Fairy Blade would be nice, like you've already mentioned. Another choice would be Fairy Rush, which would wind up to be an alternative to the move Dragon Rush. This would indeed endorse aggression as I've stated earlier, but probably not as much as Dragon Slayer.