I was agreeing until i actually zoomed in on that picture.
http://img.finalfantasyxiv.com/lds/p...644.1375781098
you'll notice that the weapons actually ends with a pommel to the left side of the hand. There is a gap between that and the shoulder. So it does appear to be something other than a bow, but as Rubieus pointed out, concept art is concept art. Spectulation is fun, but it may not have any significance at all.
As far as the discussion of the ears go, I do also recall there being something about miqo'te possibly getting other ear types. I'll see if i can find it. That could be what it is, if it has any significance at all. Though, speculation can be fun, anyways.