The derisive multipurpose phrase does not originate from "pluck yew," but I wish it did. Ping. Ouch. That stinging penetration stuck.
Predominately American misconceptions wikipedia page.
My misconception was I thought long bows were longer than that. This looks like a regular bow to me, not a long bow. But if he says so, fine.
I read in a book, a novel so made up, the Huns developed laminated composite bows that fused a layer of sinew on one side and a layer of horn on the other, one material resists stretching the other resists compression but I do recall which does which seems to me they both resist both but that's what the book said. Wait. Horn at the handle, sinew on the ends, stretching of sinew plus compression of horn stores more energy than wood. That means you had to have stronger arms to pull it, and do that on horseback. Pluck yew.