That's not a harp on the bow lol. There are only 4, maybe 5 strings if one is hidden, and that's nowhere near enough. If that's a harp, it's a very poorly designed one, and I doubt it would be poorly designed based on the rest of the stuff in the pic.

It looks more like either an elaborate compound bow, a quiver attached to the bow like a real-world hunting bow, or something else entirely.