Both, the BFI is initiated after AAF has come into effect, so it and any other Jackals in the same squadron will move 80cm and are on BFI at the same time. This is the same principle as when ramming, you speed up, moves, brace just before impact (ld passed in order to hit at all, thus you risk taking damage and may therefore attempt to BFI) and then smash into/through the target.
So in effect this would reduce weapon strength twice as both AAF and BFI halves weapons.