[@Enkryption]: Mmm, a couple things here.

Harpy feathers are pretty ordinary feathers, so I'm not really sure how they'd be useable in that way. I know "shoot feathers as projectiles" isn't exactly uncommon but they're usually more inherently magical entities or the feathers have unique properties, harpies are in most respects in-universe "ordinary" in terms of their physical properties.

Also they're not really [i]beasts[/i] per say, aside from being less human(in their wings and legs and all that) then the non-monstrous races. They're actually one of the most commonplace monstrous races since they get employed as couriers.