This is a mash up of “another string to his bow” (an Australian and British idiom meaning an extra skill or qualification), “another arrow to his quiver” (American version of the same), and “a feather in his cap” (an honor or award). The confusion certainly lies in the meanings of both phrases which are similar, but also that bows and arrows conjure up feathers in headdresses. Arrows also contain feathers at the ends. I can also see the speaker confusing bow with boa, and that of course leads to feather boas, a must have item in burlesque shows. Lots going on in this malaphor. Thanks to Eric Marsh for sending this one in.