While there's no doubt Dasbus could resell them, in reality I don't think a half size too large is that big of a deal. Because they're boots (and the lacing therefore goes up the ankle), as long as you lace/tie them relatively tightly, that should help pull you to the back of the boot. People talk a lot about heel slip, but in my experience, a little bit of break-in can go a long way. I would wager a guess that you could probably form a heel pocket that would prevent heel slip on a boot a full size (or even size and a half) too big.
Obviously, switching for the perfect size is ideal, but if that's not doable...I wouldn't sweat it all that much.