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.
This slippery malaphor is a mash up of “feather your own nest” (use power and prestige to one’s advantage selfishly) and perhaps “know which side your bread is buttered on” (to be loyal to the person who will benefit you the most). “Bread and butter” (someone’s livelihood or source of income) could also be a player here. There is also an Hungarian expression -több mindent jelenthet – roughly translated “butter one’s bread on both sides” and meaning leaving nothing for others to argue or complain. My ol’ pal indicates “buttering your own bread” (using power to gain income selfishly) may also be part of this mix up.
This is a mixture of “feathering your own nest” and “lining your pockets”, both sayings meaning making lots of money, sometimes illegally, at the expense of others or disregard for others. This malaphor might be an improvement over both sayings.